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m1omg
2007-Sep-18, 06:24 PM
Hello, I have the following questions;
1.When will Sun become so bright that Mercury will become molten?
2.When will Sun become bright enough to melt Venus?
3.What will be the temperature on our home planet then?

JohnBStone
2007-Sep-18, 06:53 PM
Hello, I have the following questions;
1.When will Sun become so bright that Mercury will become molten?
2.When will Sun become bright enough to melt Venus?
3.What will be the temperature on our home planet then?
They are already both hot enough to melt Lead, Tin and Zinc.

astromark
2007-Sep-18, 07:20 PM
Not wanting to start a riot, but the sun is not getting brighter at all. Its understanding what is actually happening to the sun over a 5 billion year period. Our sun is estimated to be 4.5 billion years into its estimated life span of 9 to 10 billion years as a main sequence star. At or near the end of this period the sun will begin to expand. Engulfing Mercury and Venus and yes planet Earth will be removed from the habitable environment list. Not vaporised but stripped of atmosphere and life... Do oh! We will have long since moved off or worse. At some point further down its evolutionary path it will shed material at an alarming rate and further reduce to a red dwarf. Unfortunately the solar systems inner planets would have been long since been sterilized. What will become of Earth? Imagine a cold Grey globe giving no clue to its wonderful past.
At this point I will add that these events are some billions of years away into the future. What we are seeing today is not part of the suns end days... just the normal cycle of events.
And now watch as the experts jump in and spoil my story of things as I see them... nothing is set in concrete.:)

Tim Thompson
2007-Sep-18, 08:27 PM
It does appear that Earth will survive the first red giant phase of solar evolution, but it's a close call. However, it will not survive the AGB phase (http://www.strw.leidenuniv.nl/~woitke/AGB_popular.html) of solar evolution. See my article "Final Destiny" in the newsletter of the Los Angeles Astronomical Society (http://www.laas.org), April 2007 issue, for a better time line & explanation.

EDG
2007-Sep-18, 09:23 PM
And now watch as the experts jump in and spoil my story of things as I see them... nothing is set in concrete.:)

The "story as you see it" is NOT what is being asked for - what's being asked for is a current mainstream scientific prediction of our star's evolution. Yet again - if you don't know much about the topic at hand then it's best to not answer the question, since your fanciful musings are just going to end up confusing the issue.

For starters, the sun *is* slowly (over geological time) getting brighter, even while it's on the main sequence today. When it becomes a subgiant in about 5 billion years, and then a Red Giant, and then a Horizontal Branch giant, and then an AGB giant (in fairly rapid succession after the subgiant phase) it will be a lot more luminous than it is now (and larger, obviously).

At the end of the AGB phase it will pulsate (much like the star Mira) shed its outer layers to reveal a *white* dwarf (not a red one as you claim).

Otherwise, Tim covered everything else.

EDIT: Oh yeah - Mercury should be fine (if not a bit hotter) throughout all of the sun's Subgiant phase, but when Sol enters the Red Giant phase then it'll get swallowed up. Venus might avoid being swallowed during the RGB phase (just) but will probably be rendered molten/start to evaporate when the Red Giant is largest/brightest. If Venus survives, then what's left of it (probably a big ball of refrozen basalt) will remain instact during the HB phase, and then get consumed completely in the AGB phase. So Mercury gets swallowed first in the RGB phase , then Venus in th AGB phase, and then probably the Earth later in the AGB phase too.

astromark
2007-Sep-19, 06:52 AM
Oops.. yes, white dwarf not a red one...

and thank you but I am well capable of understanding the original question which I still think I answered in my own way which is and always should be not taken as the last word on anything... And NO I will not be, not answering questions just because you do like my style of answer... I think my contributions are helpful if not complete. I do not know everything it would seem. If you do not like the way I answer questions then do not read them. I am not compulsory. Just offering my answer. There is always going to be different points to offer. I would have thought that is the point.

EDG
2007-Sep-19, 07:53 AM
Oops.. yes, white dwarf not a red one...

and thank you but I am well capable of understanding the original question which I still think I answered in my own way which is and always should be not taken as the last word on anything... And NO I will not be, not answering questions just because you do like my style of answer... I think my contributions are helpful if not complete. I do not know everything it would seem. If you do not like the way I answer questions then do not read them. I am not compulsory. Just offering my answer. There is always going to be different points to offer. I would have thought that is the point.

I'm afraid that really isn't the point. Your style isn't the issue, it's the content of your posts. In your response here you got several obvious facts wrong that you would have realised were incorrect had you bothered to do a little research before you answered (or known about the subject to start with).

When someone asks a question - especially a specific one like this - they expect someone who actually knows the answer to respond to them. They don't want someone who either knows nothing at all about the subject and just guesses, or who writes what he thinks is true based on assumptions rather than actual knowledge. Either you know the answer or you don't, and if you don't then you don't have any reason to answer the question - so leave it to the people who do know (of which there are several here) to answer it.

Feel free to opinionate all you like on other threads that are devoted to vague philosophical meanderings, but if someone is asking a direct question like this then it's facts that are required, not opinions.

mfumbesi
2007-Sep-19, 08:43 AM
Feel free to opinionate all you like on other threads that are devoted to vague philosophical meanderings, but if someone is asking a direct question like this then it's facts that are required, not opinions.

I think you are being too harsh on astromark, I know s/he can defend himself, but I couldn't help it. You could have phrased your "rebuke" differently, he is a regular and a likable poster. We don't have to like each other but we still have to be courteous/civil to each other.

astromark
2007-Sep-19, 10:38 AM
Hello, I have the following questions;
1.When will Sun become so bright that Mercury will become molten?
2.When will Sun become bright enough to melt Venus?
3.What will be the temperature on our home planet then?

1/Firstly I want to show you your error... The sun is not brightening. I responded correctly.I have an issue with the word bright. There is more than that happening. It might be increasing its energy output which includes across the spectrum light and all sorts of other radiation. Its not the brightness that heats up the planets. brightness is just light.
2/No it might not ever melt Venus but, will blow its atmosphere away.
3/ I do not know the answer to this.

Thanks for that support mfumbesi.

EDG., Vague philosophical meanderings, you said; That was not my intention.
We are fallible, and have personalities... are you always right?

:)I am not.

EDG
2007-Sep-19, 03:28 PM
I think you are being too harsh on astromark, I know s/he can defend himself, but I couldn't help it. You could have phrased your "rebuke" differently, he is a regular and a likable poster. We don't have to like each other but we still have to be courteous/civil to each other.

I'm being pretty civil. My point is that if you don't know the answer to questions then guessing or making stuff up doesn't help anyone. It doesn't matter how "likable" you are - if you're wrong then you're wrong and should be called on it.

Other experts who DID know exactly what they were talking about chipped in and answered the question properly, so what purpose did Astromark's response serve here? It didn't add anything useful to the answers, and indeed was inaccurate on several counts. And if the experts hadn't responded and only Astromark had replied, the OP would have been left with an answer that was incorrect and inaccurate, which wouldn't have been useful at all.

Why would anyone post an answer that they're not sure is correct? Shouldn't they at the very least check their facts before they post if there's a hint of doubt?

EDG
2007-Sep-19, 03:35 PM
1/Firstly I want to show you your error... The sun is not brightening. I responded correctly.I have an issue with the word bright. There is more than that happening. It might be increasing its energy output which includes across the spectrum light and all sorts of other radiation. Its not the brightness that heats up the planets. brightness is just light.
2/No it might not ever melt Venus but, will blow its atmosphere away.
3/ I do not know the answer to this.


1) Again, this is wrong. You did not respond correctly. The sun is brightening, even by your definition - as its energy output and general luminosity increases then it also visibly brightens. And the visible light is part of the spread of EM radiation that heats up objects that are orbiting the star. And more to the point, it's a bit strange to take the OP so literally. It's obvious that he meant "increase in luminosity", so why nitpick over that?

2) Have you actually crunched numbers for this? I don't believe you have. According to one stellar evolution model (from the Geneva stellar evolution grids), the sun will get to a radius of about 0.56 AU and luminosity of 1500 sols at the end of the RGB stage - if Venus is still at 0.7 AU then its blackbody temperature would be around 4600K, more than enough to melt it and blast away its atmosphere (though probably not enough to evaporate the surface, unless it gets physically eroded away by the solar wind).



EDG., Vague philosophical meanderings, you said; That was not my intention. We are fallible, and have personalities... are you always right?

:)I am not.

Then don't answer. Science is about facts, not opinions or personalities. And when I answer questions I do my best to provide as accurate an answer as possible - otherwise I don't answer it. If someone asked you a mathematical question then guessing an answer when you don't have a clue how to calculate it isn't useful, so don't guess here.

Neverfly
2007-Sep-20, 11:06 AM
EDG, Your statements "don't have a clue" etc are not warranted.

Your entire series of posts here have been distracting more than helpfull.

Whenever dealing with a simple question that has a complex answer, many different facts may be left out by some and brought up by others. No one person has all factors, all facts, all events and possibilites accounted for. That is the point of discussion.

If a person posts something that is incorrect, you offer a correction.

You don't tell them how ignorant they are and to sit down and shut up.

Learning is a process that includes being wrong and being corrected sometimes. That includes you. It includes me.
And your over-all arrogance detracts from whatever factual evidence you are trying to bring to the table.

...oh... And if you are thinking about a good witty rebuke to give to me I would advise against it. I'm hot-headed enough to carry an argument longer than you can.

You would be much better off just admitting your arrogant chastizing was un-called for and correcting yourself while you are at the task of trying to correct others.
http://www.cosgan.de/images/smilie/boese/a037.gif

Ken G
2007-Sep-20, 11:50 AM
I actually think there may be an aspect of the question in the OP that has not yet been answered. It seems to me the OP is asking, what luminosity would the Sun need to melt Mercury and Venus, correct? Then you need to know that the surface temperature of a planet outside the Sun (which Mercury will not be when the sun is a giant) scales as the fourth root of the luminosity (that's because the planet emits energy like its surface temperature to the fourth power, and this must scale with the Sun's luminosity to stay in balance). The surface temperature also scales like the inverse square root of distance. The distance effect means Mercury is about a factor of 1/.4^.5 = 1.6 times hotter than the Earth's 300 K, so that's about 500 K. That might need to double to melt the planet, so we need to bring in the luminosity effect and get the luminosity to rise by the factor of 2 to the fourth power, or about a factor of 16 roughly. At least a factor of 10, let's say. The Sun won't do that on the Main Sequence, but will shortly thereafter. Of course, when Mercury is inside the Sun, it will be subjected to very high temperatures-- but the Sun could have melted it even before that point if it were evolving slowly enough. Venus would need higher luminosities still-- due to its greater distance it gets about 3 times less energy per square meter so would need 3 times higher solar luminosity to melt it than does Mercury, so maybe 30-50 times the current solar luminosity. That would also happen in the Sun's red giant phase, even without enveloping Venus (which it may well do).

EDG
2007-Sep-20, 03:56 PM
EDG, Your statements "don't have a clue" etc are not warranted.

Your entire series of posts here have been distracting more than helpfull.

Really now. I've provided answers to the OP's questions. What have you done?



Whenever dealing with a simple question that has a complex answer, many different facts may be left out by some and brought up by others. No one person has all factors, all facts, all events and possibilites accounted for. That is the point of discussion.

Rubbish. This isn't a discussion - someone asked a specific question, and wanted specific answers. Tim and myself provided correct answers. Astromark gave a waffly, uninformed response that was incorrect (which he often does), and I called him on it this time.



If a person posts something that is incorrect, you offer a correction.

I did.


You don't tell them how ignorant they are and to sit down and shut up.

When someone consistently provides incorrect answers, doesn't bother to do research, and then insists he has a right to spout his ignorant opinions then that is exactly what I do.

When someone asks a specific question like this, that does actually have a specific answer, you don't want the answer that "feels the most truthy" from the list of responses. I know that's what some people seem to think - but the reality is that the OP wants an answer that is actually correct, or at least as close as possible to what science thinks is correct.

If I was to ask how close a moon had to be to a planet before it broke up then I'd expect someone to answer who knew about roche limits and how the densities of the bodies involved affected that. If someone said "well, I know nothing about the subject but here's what I think, and I reckon it's about five planetary radii and that's my story which I'm sticking to until an 'expert' comes along" then I'd be wondering why that person wasted my time and their time writing that useless post.



Learning is a process that includes being wrong and being corrected sometimes. That includes you. It includes me.

And that includes Astromark too. But if you think I'm wrong about something here, then by all means point it out. I've very confident that I'm not though.



And your over-all arrogance detracts from whatever factual evidence you are trying to bring to the table.

It's up to you if you want to ignore the factual evidence. I've studied stellar evolution for a very long time and know that I'm at the very least pretty close to correct (based on current stellar evolution models) about this. If you think that confidence is "arrogance" then that's up to you.



...oh... And if you are thinking about a good witty rebuke to give to me I would advise against it. I'm hot-headed enough to carry an argument longer than you can.

You'd be foolish to do so. If you're willing to argue that it's preferable to allow people who don't know about a subject to respond to specific questions rather than allow the experts who DO know about it to answer it and to correct others for providing wrong answers, then I don't think there's much hope for this as a science board. And I'm certainly not going to say "OK, you're right, I'll just let people who don't know about the subject carry on confusing people with their uninformed responses".



You would be much better off just admitting your arrogant chastizing was un-called for and correcting yourself while you are at the task of trying to correct others.

I think it says a lot more about you that you feel threatened by someone who is actually making the effort to offer the correct answers, and that you want to make an issue over the fact that I am sick and tired of people giving flawed or incorrect answers. It's one thing for someone to at least show that they do know about the subject and admitting they have holes in their knowledge - that's fine. But like I said, giving an obviously completely uninformed opinion is not a satisfactory response to this sort of question, and I have every right to ask in no uncertain terms that someone who does that should stop doing it.

Neverfly
2007-Sep-20, 04:20 PM
Really now. I've provided answers to the OP's questions. What have you done?
Childish and irrelevent response.

Rubbish. This isn't a discussion - someone asked a specific question, and wanted specific answers. Tim and myself provided correct answers. Astromark gave a waffly, uninformed response that was incorrect (which he often does), and I called him on it this time.
Astromark made it clear what he was saying and did not claim to be providing a pure scientific answer.
and yes, it IS a discussion.

I did.
Agreed. However, the manner in which you addressed Astromark was not a correction it was an insult and a request for him to be silent unless spoken to as you would a little child. It was degrading and unprofessional.


When someone consistently provides incorrect answers, doesn't bother to do research, and then insists he has a right to spout his ignorant opinions then that is exactly what I do.
Can you back up the claim that an individual poster repeatedly and consistantly spouts rubbish, inconsistant answers and ignorant opinions?
If a person has the wrong idea about something all you need to do is say what the correct answer is.
You don't need to insult them in the process.


When someone asks a specific question like this, that does actually have a specific answer, you don't want the answer that "feels the most truthy" from the list of responses. You want an answer that is actually correct.
There are more than one poster replying.
You can teach or you can act like the hind end of a donkey and repel anyone who would have listened to you.


If I was to ask how close a moon had to be to a planet before it broke up then I'd expect someone to answer who knew about roche limits and how the densities of the bodies involved affected that.
Agreed. And answers were given by yourself and Tim.


If someone said "well, I know nothing about the subject but here's what I think, and I reckon it's about five planetary radii and that's my story which I'm sticking to until an 'expert' comes along" then I'd be wondering why that person wasted my time and their time writing that useless post.
Actually, it was you who said he knows nothing. So far you have used the words, "ignorant", "opinions" and "does no research"
He never said anything about "Sticking to the story til an 'expert' comes along"
I think you have assigned your own malisciousness to another individual.


If you think I'm wrong about something, point it out. I've very confident that I'm not.
I did.
You didn't like to hear it. The fact is that you were wrong then and are still wrong now.
I'm very confident that you are.
You meant to say I'm not I've.

It's up to you if you want to ignore the factual evidence. I've studied stellar evolution for a very long time and know that I'm at the very least pretty close to correct (based on current stellar evolution models) about this. If you think that confidence is arrogance then that's up to you.
I ignored no factual evidence.
I admire and respect your knowledge. It is your attitude and abusive nature in talking to another that disturbed me. Displayed in:
Actually, it was you who said he knows nothing. So far you have used the words, "ignorant", "opinions" and "does no research"
He never said anything about "Sticking to the story til an 'expert' comes along"<< From above.

You'd be foolish to do so. If you're willing to argue that it's preferable to allow people who don't know about a subject to respond to specific questions rather than allow the experts who DO know about it to answer it and to correct others for providing wrong answers, then I don't think there's much hope for this as a science board.

Again, several statements fraught with arrogance.
I would not be foolish for the following reasons:
1)Specific questions asked on an open board do not only teach the one who asked the question. All others who read can learn something.
2) Individuals that post are aware that they may have gotten a fact wrong or may have messed up calculations entirely. In a polite discussion they can feel open to correction and critisism-withOUT being called an "idiot" by one who thinks he's Top of the Experts.

If you think that these reasons give you no hope for a science board than you are ooposed to learning, the natural psychology of humans, the ability to teach and the ability to correct.


I think it says a lot more about you
Irrelevent.

that you feel threatened by someone
I don't feel threatened. Vague assumption. There's not need to boost your ego. Get over yourself.

who is actually making the effort to offer the correct answers,
Making an effort to giuve the correct answers is fine. It was the arrogant insulting degrading attitude that bothered me. Please stay on topic.

and that you want to make an issue over the fact that I am sick and tired of people giving flawed or incorrect answers.
Then I certainly hope you never go into teaching.

It's one thing for someone to at least show that they do know about the subject and admitting they have holes in their knowledge - that's fine.
Funny. That is exactly what Astromark did.

But like I said, giving an obviously completely uninformed opinion is not a satisfactory response to this sort of question.
Agreed.
That is where polite correction comes in.
Teaching not just the asker of the question but seizing the chance to teach others as well.

As stated in my first post. I can disect each one of your defensive and emotional posts and expose the ONLY flaw in your posts as long as you would like me to. Im tireless.
Your knowledge is admirable. Your responses in providing correct information justifiable.
Your arrogance and insulting comments combined with advising others to not speak is uncalled for and counter productive to a learning environment.
You can continue to deny your error and I can continue to expose it for you until you get over your ego and admit to your mistake.
OR. a mod steps in and tells Both of us to knock it off.
The choice is yours.

EDG
2007-Sep-20, 04:26 PM
I'm not wasting my time arguing with you, Neverfly, particularly since you've pretty much admitted your sole aim is to troll for responses.

I am not in error and will not admit that I am. That is the end of the matter.

Neverfly
2007-Sep-20, 04:29 PM
I'm not wasting my time arguing with you, Neverfly, particularly since you've pretty much admitted your sole aim is to troll for responses.
Please quote me where I "admitted that my sole aim is to 'troll' for responses."



I am not in error and will not admit that I am. That is the end of the matter.

Ignorance is bliss.

ETA:Since EDG bows out-I hope that these few posts here serve as a reminder to others what is proper correction as opposed to throwing a fit and telling other posters to "Be quiet" rather than seize the opportunity to teach, captivate and inspire interest without fear of being degraded and insulted in the process.

Neverfly
2007-Sep-20, 07:34 PM
http://www.bautforum.com/questions-answers/59842-how-violent-process-turning-into-white-dwarf.html
Interesting find.

astromark
2007-Sep-20, 07:44 PM
1/Firstly I want to show you your error... The sun is not brightening. I responded correctly.I have an issue with the word bright. There is more than that happening. It might be increasing its energy output which includes across the spectrum light and all sorts of other radiation. Its not the brightness that heats up the planets. brightness is just light.
2/No it might not ever melt Venus but, will blow its atmosphere away.
3/ I do not know the answer to this.
:)I am not.
astromark Oops.. yes, white dwarf not a red one...

and thank you but I am well capable of understanding the original question which I still think I answered in my own way which is and always should be not taken as the last word on anything... And NO I will not be, not answering questions just because you do like my style of answer... I think my contributions are helpful if not complete. I do not know everything it would seem. If you do not like the way I answer questions then do not read them. I am not compulsory. Just offering my answer. There is always going to be different points to offer. I would have thought that is the point.
Not wanting to start a riot, but the sun is not getting brighter at all. Its understanding what is actually happening to the sun over a 5 billion year period. Our sun is estimated to be 4.5 billion years into its estimated life span of 9 to 10 billion years as a main sequence star. At or near the end of this period the sun will begin to expand. Engulfing Mercury and Venus and yes planet Earth will be removed from the habitable environment list. Not vaporised but stripped of atmosphere and life... Do oh! We will have long since moved off or worse. At some point further down its evolutionary path it will shed material at an alarming rate and further reduce to a red dwarf. Unfortunately the solar systems inner planets would have been long since been sterilized. What will become of Earth? Imagine a cold Grey globe giving no clue to its wonderful past.
At this point I will add that these events are some billions of years away into the future. What we are seeing today is not part of the suns end days... just the normal cycle of events.
And now watch as the experts jump in and spoil my story of things as I see them... nothing is set in concrete.


Thanks for that support mfumbesi.

EDG., Vague philosophical meanderings, you said; That was not my intention.
We are fallible, and have personalities... are you always right?

The order of the above postings is not correct...
Nor is some of the things I have said,,,
I said that.
I stand by what I said and feel offended at your outbursts EDG
In my opinion you have been un-necessarily abusive and directly insulting to me. I will not withdraw a single ward of my posts as I feel, believe that this forum is a place for informative opinion and fact. There always must be discussion and opinion. I am not interested in your world of unbending pedantic correction... It is my opinion that you have gone to Farr in correcting what you saw as error. I have expressed myself as a different person as you. For that I am grateful.
Thank you Neverfly... Your thoughts and mine are as tolerance and understanding dictate.
EDG. I will wait for your apology. A long time? prove me wrong.!

Serenitude
2007-Sep-20, 08:11 PM
This thread has gotten off track, and has gone outside the acceptable bounds of civility and decorum. Keep it on topic, no ad-homs, and civil.

Paracelsus
2007-Sep-20, 09:20 PM
It does appear that Earth will survive the first red giant phase of solar evolution, but it's a close call. However, it will not survive the AGB phase (http://www.strw.leidenuniv.nl/~woitke/AGB_popular.html) of solar evolution. See my article "Final Destiny" in the newsletter of the Los Angeles Astronomical Society (http://www.laas.org), April 2007 issue, for a better time line & explanation.

Tiny request, Tim Thompson: If/when convenient, could you look at that thread I started about the planet found around a white dwarf at near-Earth orbital distance? I read your previous posts RE end-stage evolution of stars like our Sun, but I'm wondering how these new results fit into the general picture. I couldn't get hold of any papers for these new findings, sorry.

Edit: EDG did provide some helpful answers (thanks for that! :)), but it appears that you, Tim, are an expert in this particular area of Astronomy, and I was asking the question RE the AGB phase that you had posted about earlier.

Paracelsus
2007-Sep-20, 09:30 PM
According to one stellar evolution model (from the Geneva stellar evolution grids), the sun will get to a radius of about 0.56 AU and luminosity of 1500 sols at the end of the RGB stage - if Venus is still at 0.7 AU then its blackbody temperature would be around 4600K, more than enough to melt it and blast away its atmosphere (though probably not enough to evaporate the surface, unless it gets physically eroded away by the solar wind)

Ooooh cool! :) Is it online, and, if it is, would you happen to have the link to that by any chance, EDG?

Neverfly
2007-Sep-21, 12:01 AM
(snip)

Thanks for that support mfumbesi.

(snip)

The order of the above postings is not correct...
Nor is some of the things I have said,,,
I said that.
I stand by what I said and feel offended at your outbursts EDG
In my opinion you have been un-necessarily abusive and directly insulting to me. I will not withdraw a single ward of my posts as I feel, believe that this forum is a place for informative opinion and fact. There always must be discussion and opinion. I am not interested in your world of unbending pedantic correction... It is my opinion that you have gone to Farr in correcting what you saw as error. I have expressed myself as a different person as you. For that I am grateful.
Thank you Neverfly... Your thoughts and mine are as tolerance and understanding dictate.
EDG. I will wait for your apology. A long time? prove me wrong.!

You're welcome Astromark, however, I must point out that if you were corrected for inaccurate information then it makes no sense to stand by that information regardless of the manner in which the correction was presented.
It is more honorable at least, to admit to the error on your part and look for more knowledge and do some research to find the correct information.

Speculating what might happen has gotten a response that should have pointed you in the right direction to gather fact so you would not need to speculate on this topic in the future, you could simply state the science of it.

Hopefully Tim Thomspon and EDG_ will respond to Paracelsus' request and we can all learn more on something that is already a fascinating topic.;)

BigDon
2007-Sep-21, 12:34 AM
Hey, if the girl fight is over, can somebody explain to me what asymptotic means?

(I say girl fight because most of this thread is about as dignified as one.)

EDG your new call sign is now "Edgey"

Neverfly
2007-Sep-21, 12:41 AM
http://en.wikipedia.org/wiki/Asymptotic_analysis

Ouch! BigDon, if you are calling me a girl, we are going to have to head behind the bandstands and correct this wildly inaccurate image of my persona;)

BigDon
2007-Sep-21, 12:48 AM
http://en.wikipedia.org/wiki/Asymptotic_analysis

Ouch! BigDon, if you are calling me a girl, we are going to have to head behind the bandstands and correct this wildly inaccurate image of my persona;)

My turn to say ouch. I read that and I still don't get it.




No problem. Since you're my friend and all, I promise not to hit you in the grill or kick you in the stones.

Neverfly
2007-Sep-21, 12:53 AM
My turn to say ouch. I read that and I still don't get it.




No problem. Since you're my friend and all, I promise not to hit you in the grill or kick you in the stones.

Good. In return I promise not to break anything or cause internal damage to any vital organs:p
Another Ouch for ya:
http://en.wikipedia.org/wiki/Asymptotic_expansion

An asymptotic expansion of a function f(x) is in practice an expression of that function in terms of an infinite series, the partial sums of which do not (necessarily have to) converge; but such that taking any initial partial sum provides an asymptotic formula for f. The idea is that successive terms provide a more and more accurate description of the order of growth of f.

EDG
2007-Sep-21, 01:04 AM
Ooooh cool! :) Is it online, and, if it is, would you happen to have the link to that by any chance, EDG?

http://obswww.unige.ch/~mowlavi/evol/stev_database.html

They're a bit out of date now though, but I've been using them for the past few years to get the stellar parameters for my worldbuilding models. They're broadly accurate though. I'm not sure you'll be able to make much sense of it if you're not an astrophysicist though - there's papers explaining the models and then there's vast tables (the evolution grids) showing all sorts of parameters as the star ages.

There's better ones around now that I haven't had a chance to really look at, that have tables consisting of thousands of rows of data...


However, I've also written this summary of stellar evolution (http://www.evildrganymede.net/rpg/traveller/stellar.htm) for the layman (doesn't cover everything, but it covers the basics). So you might find that useful.

EDG
2007-Sep-21, 01:16 AM
Hey, if the girl fight is over, can somebody explain to me what asymptotic means?

An asymptote is a line on a graph that moves ever closer to a particular value, but never reaches it. It's called the Asymptotic Giant branch because when you plot out the evolution on the star on a Herzsprung-Russell Diagram, the track followed by the AGB stage is almost parallel (i.e. asymptotic) to the track followed during the earlier Red Giant branch stage.

You can see what I mean on the graph on this page:
http://iapetus.phy.umist.ac.uk/Teaching/IntroAstro/StellarEvolution.html

BigDon
2007-Sep-21, 01:21 AM
EDG, wow, I never realized that bit about the low mass stars' helium cores growing like that. Makes sence. But what happens after that? Is it concidered burnt out?

BigDon
2007-Sep-21, 01:24 AM
Oh, you slipped in a post while I was typing, I meant from your paper.

EDG
2007-Sep-21, 02:16 AM
EDG, wow, I never realized that bit about the low mass stars' helium cores growing like that. Makes sence. But what happens after that? Is it concidered burnt out?

I've not really found a good answer for that anywhere (possibly because it'd be tens of billions of years before we see one of these). It sounds as if the star's hydrogen just turns completely to helium and then it just sits there doing nothing else - the He can't be fused by the star, and I don't think it collapses, it just literally burns itself out. (not sure what a Helium Dwarf would look like either - eventually I guess it'd look like a very big gas giant once it cooled enough).

astromark
2007-Sep-21, 05:49 AM
Why so long before we see one of these? Has this not happened some place we can see? Is that evidence that it might not ever actually happen that way.? With every thing you teach me I seem to have more questions... in need of help:)mark.

EDG
2007-Sep-21, 06:20 AM
Why so long before we see one of these? Has this not happened some place we can see? Is that evidence that it might not ever actually happen that way.? With every thing you teach me I seem to have more questions... in need of help:)mark.

Because the stars that have such low masses that they can only become Helium Dwarfs are very long lived. There simply hasn't been enough time since the universe formed for them to burn through all their hydrogen. Give it another 10 billion years or so and you might start seeing the most massive of these Helium Dwarf progenitor stars becoming a Helium Dwarf. The lowest mass ones will keep burning their fuel for trillions of years after that though.

astromark
2007-Sep-21, 06:29 AM
wow... thx, Thats stability.
but, seriously are there any of these in our observable area.. ?

EDG
2007-Sep-21, 06:34 AM
but, seriously are there any of these in our observable area.. ?

I thought I was being pretty clear there - there hasn't been enough time for them to form. So obviously that means there aren't any nearby (or anywhere else in the universe for that matter).

There are plenty of stars that will eventually become Helium Dwarfs - any red dwarf (M V) stars for example. But those are the ones that take hundreds of billions or trillions of years to use up all their hydrogen fuel.

astromark
2007-Sep-21, 11:42 AM
I thought I was being pretty clear there - there hasn't been enough time for them to form. So obviously that means there aren't any nearby (or anywhere else in the universe for that matter).

There are plenty of stars that will eventually become Helium Dwarfs - any red dwarf (M V) stars for example. But those are the ones that take hundreds of billions or trillions of years to use up all their hydrogen fuel.

Its the language you use.. I am with you on your explanation of why I can not see a Helium Dwarf.
That is not what I am asking. THE LOW MASS STAR that might become one...where?

Just take another look at how you have responded....

I have read your posts and understood you. This is your post so I asked what I thought was a reasonable question from it....
You said. "Because the stars that have such low masses that they can only become Helium Dwarfs are very long lived. There simply hasn't been enough time since the universe formed for them to burn through all their hydrogen. Give it another 10 billion years or so and you might start seeing the most massive of these Helium Dwarf progenitor stars becoming a Helium Dwarf. The lowest mass ones will keep burning their fuel for trillions of years after that though."
All I am asking is where can I find one of these (potential) Helium Dwarfs candidates....

EDG
2007-Sep-21, 03:33 PM
Its the language you use.. I am with you on your explanation of why I can not see a Helium Dwarf.

I don't know about you, but I'm using plain english.



That is not what I am asking. THE LOW MASS STAR that might become one...where?

All I am asking is where can I find one of these (potential) Helium Dwarfs candidates....

That's not what you asked. It helps if you phrase your question clearly.

First you asked "why so long before we can we see one of these?" (referring to Helium Dwarfs), so I answered that.

Then you asked "are there any of these in our observable area?". To which I said, "no, obviously not" (again, referring to Helium Dwarfs since that is what we're talking about and you didn't specify anything else).

It's only now that you've mentioned that you were actually referring to the low mass progenitor stars, and not to the Helium Dwarfs themselves (that everyone else was talking about).

But as I said (and I mentioned in the evolution summary), the low mass stars are everywhere. M V stars are the most common in the universe, and the HD progenitors include a good chunk of the lower mass K V stars. So any red dwarf star (eg Proxima Centauri, Barnard's Star) will end up as one. So they're all over the place.

neilzero
2007-Sep-21, 09:42 PM
How about the lowest mass K stars? Will they ever fuse helium? Perhaps some will and some won't. I am frequently amazed that astronomy draws sharp lines, about future events. Couldn't a massive, very fast impactor, trigger helium fusion in a star that otherwise would not fuse helium? Conversely, perhaps a massive impactor could prevent helium fusion in a star that otherwise would have fused helium? Is there not at least a narrow band of uncertainty? Neil

EDG
2007-Sep-21, 11:32 PM
How about the lowest mass K stars? Will they ever fuse helium? Perhaps some will and some won't.

As I understand, the limit is around 0.8 solar masses. Which everything from at least K5 V downwards.


I am frequently amazed that astronomy draws sharp lines, about future events. Couldn't a massive, very fast impactor, trigger helium fusion in a star that otherwise would not fuse helium? Conversely, perhaps a massive impactor could prevent helium fusion in a star that otherwise would have fused helium? Is there not at least a narrow band of uncertainty? Neil

Not really. Your "impactor" would have to be another star - at least massive enough to bring the combined star above the aforementioned 0.8 solar mass limit. Even if it was driven by the pressure of the impact alone, it wouldn't be sustainable because that pressure is instantaneous.

neilzero
2007-Sep-22, 12:54 PM
Hi astromark: I don't want you to quit posting. The mainstream view point is often hard to identify. In this case, I believe the mainstream opinion is the Sun is brightening about 2% per billion years and will continue to brighten at about this rate for at least 3 billion more years.
Thus brightening over periods as short as one million years (average 0.002%) can be considered negligible, which makes your assertion correct.
A few astronomers class our Sun as a variable star, because there are tiny brightness variations over periods of hours, days and centuries. I don't think it is wrong to concider these variations negligible. I noted one poster was adding a V after each star he mentioned: ie K5.34V M2.1V. Perhaps the V has a meaning other than variable. If we want to think parts per trillion, then likely all stars are variable.
Persons wishing to debunk greenhouse warming often infer several percent increase in our Sun's brightness in the last century or two, but a few parts per million or less better fits the data, I think.
I don't think we can support more than 2% warming per billion years as there apparently were no ice ages the first 3.5 billion years as we should expect if the Sun was even 10% cooler then. Neil

StupendousMan
2007-Sep-22, 02:27 PM
I noted one poster was adding a V after each star he mentioned: ie K5.34V M2.1V. Perhaps the V has a meaning other than variable.

It means "luminosity class five", which means that the star is fusing hydrogen to helium in its core. Other terms used to describe stars of luminosity class five are "main sequence" and "dwarf".

There are many web sites which discuss spectral classification; you might look at

http://spiff.rit.edu/classes/phys301/lectures/class/class.html

for example.

EDG
2007-Sep-22, 03:24 PM
Hi astromark: I don't want you to quit posting. The mainstream view point is often hard to identify. In this case, I believe the mainstream opinion is the Sun is brightening about 2% per billion years and will continue to brighten at about this rate for at least 3 billion more years.

It's brightening a lot faster than that. It depends on the evolution model you use, but roughly speaking the sun settled on the main sequence its luminosity was about 75% of what it is today. When it leaves in 5 billion years, it'll be more like double what it is today.

And the "V" is a roman numeral - it denotes the luminosity class of the star (in this case, Main Sequence (burning hydrogen into helium). Again, if you want a layman's guide then it's explained in my stellar evolution article (http://www.evildrganymede.net/rpg/traveller/stellar.htm).

Hornblower
2007-Sep-22, 03:26 PM
I don't think we can support more than 2% warming per billion years as there apparently were no ice ages the first 3.5 billion years as we should expect if the Sun was even 10% cooler then. Neil

Astrophysicists have estimated that the Sun started on the main sequence with only about 70% of its present luminosity.

For all we know, primordial volcanic action could have loaded the atmosphere with enough greenhouse gases to keep things warmer despite the lower solar luminosity.

Ken G
2007-Sep-22, 03:28 PM
I thought I was being pretty clear there - there hasn't been enough time for them to form. So obviously that means there aren't any nearby (or anywhere else in the universe for that matter).

There are plenty of stars that will eventually become Helium Dwarfs - any red dwarf (M V) stars for example. But those are the ones that take hundreds of billions or trillions of years to use up all their hydrogen fuel.

Aren't you the one getting on astromark's case for misleading or inaccurate information in the Q&A? Then you need to check your own facts-- we all make mistakes, but when we're rude to others about our own oversights, we should expect to be taken to task. Your description of how to evolve into a helium dwarf is of a specific type-- it applies to single stars or stars in widely separated binaries. And the helium-dwarf limit I've seen is 0.5 solar masses, not 0.8. Although I don't know which is correct, 0.8 is basically the limit for the oldest stars to have evolved off the main sequence, it would be kind of a coincidence if that was also the limit for helium dwarf evolution.

But more importantly, there are plenty of stars that form in close binaries, and their evolutionary timescales may be drastically altered by mass transfer between the stars. That's why there are helium dwarfs in our very own galaxy, right now. There is even a type of nova, which is an explosion of hydrogen gas being transferred in a binary, called a "helium dwarf nova". I can't tell astromark if any of them are near us.

Neverfly
2007-Sep-22, 03:39 PM
For me, I'm seeing a pretty wide variance in numbers here.
That is fine when some things are simply flat out uncertain.
But how uncertain?
Three different posts gave some very different numbers...

Is there a standard model? Or set of equations?

EDG_, you said it depends on which model is used...

HOw many models are there and what is the difference?
I imagine that there are different models depending on composition and type of star, is that wrong?

Also, Our sun is the closest star- quite close at that- shouldn't we have a pretty accurate idea about that star in particular?

EDG
2007-Sep-22, 03:43 PM
Aren't you the one getting on astromark's case for misleading or inaccurate information in the Q&A? Then you need to check your own facts. Your description of how to evolve into a helium dwarf is of a specific type-- it applies to single stars or stars in widely separated binaries. And the helium-dwarf limit I've seen is 0.5 solar masses, not 0.8.

I made it pretty clear that I wasn't sure of that number (though I've suspected that a lower number like 0.5 would make more sense). There's knowing enough about a subject to be able to explain something to somebody with some degree of accuracy, and knowing every single numerical detail about it. I've never claimed to know every single detail about something, but I certainly know enough about it to give a broadly accurate picture, and if I don't know something for certain then I make sure I make it clear that I don't. So kindly get off my case.

And yes, my description was of a specific type. So? If you know of others then by all means mention them too - but the article I wrote described single stars and didn't include all the possibilities in binary systems and mass-transfers. It's a brief article, not a complete guide that was intended to cover everything.

Neverfly
2007-Sep-22, 03:47 PM
Bold mine:

(snip)

But more importantly, there are plenty of stars that form in close binaries, and their evolutionary timescales may be drastically altered by mass transfer between the stars. That's why there are helium dwarfs in our very own galaxy, right now. There is even a type of nova, which is an explosion of hydrogen gas being transferred in a binary, called a "helium dwarf nova". I can't tell astromark if any of them are near us.
Bold mine:

Because the stars that have such low masses that they can only become Helium Dwarfs are very long lived. There simply hasn't been enough time since the universe formed for them to burn through all their hydrogen. Give it another 10 billion years or so and you might start seeing the most massive of these Helium Dwarf progenitor stars becoming a Helium Dwarf. The lowest mass ones will keep burning their fuel for trillions of years after that though.

Two very different answers.
One is that None exist.
The other is that some exist right here in the Milky Way.

EDG
2007-Sep-22, 05:34 PM
Two very different answers.
One is that None exist.
The other is that some exist right here in the Milky Way.

I'd like to see a cite saying where a Helium Dwarf actually exists today. While mass transfer in a binary system can change a star's evolution, I've not heard of any star that is known today that has entirely converted its hydrogen to helium with nothing else left to burn. There are evolved stars that have had their outer layers stripped off to an extent that they are a helium core surrounded by a shell of hydrogen, but that's not what is being discussed here.

The stars that I described - that formed as single stars through a normal evolutionary process - are not around today. They need a minimum of tens of billions of years to form, which is longer than the current age of the universe.

This page (http://www.kusastro.kyoto-u.ac.jp/vsnet/DNe/sn1998di.html) claims that only three Helium Dwarf Novae are known. I can't find an explanation for what a Helium Dwarf Nova actually is, but it sounds like they're talking about material being ignited around white dwarfs.

EDIT: There is a class of cataclysmic variable stars known as AM Canum Venaticorum stars (there are six known examples), but from what I can find about them, it seems these are believed to be two close white dwarf stars that are igniting Helium around them. Again, these are not what I am referring to as "Helium Dwarfs" which is a low mass main sequence star that simply burns through all its hydrogen and becomes entirely made of inert, non-fusing helium. It's possible that this is not the right name for such objects, but that is what I am talking about here (and I did put "Helium Dwarf" in quotes in my article too).

Ken G
2007-Sep-22, 07:20 PM
I've never claimed to know every single detail about something, but I certainly know enough about it to give a broadly accurate picture, and if I don't know something for certain then I make sure I make it clear that I don't. My objection was not to your error in claiming that helium dwarfs are a purely theoretical type of star, we all make mistakes-- it was to your rudeness toward astromark, when you felt that he was not following your errors closely enough.


And yes, my description was of a specific type. So? If you know of others then by all means mention them too - but the article I wrote described single stars and didn't include all the possibilities in binary systems and mass-transfers. It's a brief article, not a complete guide that was intended to cover everything.I realize the article was of limited applicability, and I have no problem with that. The error was in your failure to mention that when you categorically, and rudely, stated to astromark:


That's not what you asked. It helps if you phrase your question clearly.

First you asked "why so long before we can we see one of these?" (referring to Helium Dwarfs), so I answered that.

Then you asked "are there any of these in our observable area?". To which I said, "no, obviously not" (again, referring to Helium Dwarfs since that is what we're talking about and you didn't specify anything else).
If we are talking about "helium dwarfs", then we clearly need to consider all the ways on can get one of those, before we intimate that someone must be a fool to wonder if any could be nearby, simply because you "already told them" there couldn't be, if they would only follow your incorrect reasoning more closely.

EDG
2007-Sep-22, 07:44 PM
My objection was not to your error in claiming that helium dwarfs are a purely theoretical type of star

I'm still waiting for you to show me an example of what I referred to as a "helium dwarf" (i.e. a solo, low mass star that has burned through all of its hydrogen). The stars that end up like this have not had enough time to reach that stage, that much is unambiguous. It would seem that you are referring to a different type of star that requires a very specific and rare set of circumstances to exist, and are erroneously claiming that today one can find (for example) a solo M V star that has reached the end of its natural evolution.



, we all make mistakes-- it was to your rudeness toward astromark, when you felt that he was not following your errors closely enough.

I wasn't in error though. It should be clear to anyone actually reading the article I wrote that it doesn't cover absolutely every possible situation that can come up in stellar evolution. It's an informal layman's guide that covers the basics of stellar evolution, that's all - it's a starting point, and it's not presented as anything more than that. I encourage people who are interested in learning more about it to pick up some stellar evolution textbooks or look at other websites.



I realize the article was of limited applicability, and I have no problem with that. The error was in your failure to mention that when you categorically, and rudely, stated to astromark

What you're complaining about here is me talking about how unclear Astromark's phrasing of his question was. He was not making it clear what he was referring to when he was talking about "these stars". I assumed (following the usual rules of english grammar) that he was talking about "helium dwarfs", and of course I said that there were none of those known to exist today, because there aren't (unless you're arguing that the universe is tens or hundreds of billion years old to allow enough time for those stars to form). He only added that he was talking about the progenitor stars right at the end, at which point I feel fairly justified in saying that he should have been a lot clearer about that to start with.



If we are talking about "helium dwarfs", then we clearly need to consider all the ways on can get one of those, before we intimate that someone must be a fool to wonder if any could be nearby, simply because you "already told them" there couldn't be, if they would only follow your incorrect reasoning more closely.

What you are referring to as "Helium Dwarfs" is evidently not what I am referring to as "Helium Dwarfs". You appear to be talking about white dwarfs igniting helium around them (or just to helium-rich white dwarfs), whereas I'm talking about the theoretical end point of low mass main sequence stellar evolution, where those stars have used up all their hydrogen.

Like I said, it should be clear to anyone with any reasonable skill in reading comprehension (and who has actually bothered to read my article) that it is clearly not a complete treatise on every single obscure aspect of stellar evolution, that it talks about solo stars only, and that I am just referring to those objects as "Helium Dwarfs" because I couldn't find a more appropriate name for them.

So kindly stop trying to find any excuse to paint me as ignorant or misleading when I'm clearly neither of those.

EDG
2007-Sep-22, 07:53 PM
Getting back to the thread topic rather than continuing the pointless attempts at assassinating my character...



Is there a standard model? Or set of equations?

I'm using the Geneva Stellar Evolution Grids. I've already acknowledged that those are somewhat old (from the early-mid 90s) and that there are newer ones that I haven't had a chance to update to yet. The newer ones are just more detailed and more accurate and take into account more recent research (particularly about convective overshooting in the stellar interior and how that affects how much hydrogen is available).

Also I am assuming we're talking about stars with metallicity roughly the same as that of our Sun. Subdwarfs and high metallicity stars generally evolve in a similar way but on different timescales, and the details are different too.



Also, Our sun is the closest star- quite close at that- shouldn't we have a pretty accurate idea about that star in particular?

Well we know a lot about how it behaves now, but when it comes to projecting into the past or the future it's still a star like any other, subject to all the horribly complicated equations that all stars are subject to... so the best we can do is come up with models that account for as much as we know about in order to make those predictions.

EDG
2007-Sep-22, 08:50 PM
Let me just say one last thing about the complaints against me here. My issue with Astromark was that he has a habit of posting responses to questions that he just doesn't know the answer to. He is not alone in this, I've noticed several others who do it too - but I have noticed that he consistently does this (I have also noticed that he sometimes answers questions and then declares them to be pointless and a waste of time), and I have called him a few times on it already. I may have come down a little hard on him because of that, but I'd already more politely made the point to him that this is not a good thing to do when answering a question.

I am well aware that he made it clear that he didn't know, but that wasn't the issue. The issue was "why answer a question that you don't know the answer to in the first place? If the best you can give is a wholly inaccurate answer then who is benefiting from your response?". (Note that I am not claiming that to answer a question one has to know every single detail about the subject with unerring accuracy, and I certainly have not claimed that I have that level of knowledge).

Astromark's original response clearly had several major, basic mistakes in it, and he still insisted that he was right despite those being pointed out to him - that's what annoyed me about it. If someone asks a question that requires expert knowledge, then they should expect that anyone who answers it should know enough about the subject to be able to do so properly. I know that if (for example) someone asked a question about the chemistry of elemental Bismuth then I certainly wouldn't try to answer the question because I know absolutely nothing about the subject. My uneducated response (on that subject) would not add anything useful to the discussion or help the original poster, and it would be a waste of my time to write anything and of readers time to read something that at best would be confusing and at worst would be completely erroneous. I am aware of where the limits of my knowledge are, and I think it's reasonable to expect that other people should realise where the limits of their knowledge are too.

To the best of my knowledge I have been accurate in my responses (and I've been as clear as possible where I've been unsure about specific numbers - and if I am unsure then I have made a reasonable effort to search for more information about it before writing anything). It should be clear that I know a lot about stellar evolution - I may not be a practising, payrolled scientist who is an expert in stellar evolution and knows every paper and every obscure stellar situation off by heart, but I've done an MSc in astrophysics, I've read a lot of papers about the subject and have been interested in and studied it for over a decade. I clearly have enough expert knowledge to be able to answer such questions with a reasonable degree of accuracy (which usually is all that is required in the first place) - though I will gladly admit that I am mistaken about something if that is proven to be the case.

Given all that, it seems to me that crucifying me for not knowing some obscure stellar situation or for not getting a number exactly right is somewhat petty and unreasonable. I have never said or implied that I know all that there is to know about any subject, and yet people are implying that I have. I also do not believe that it is "arrogant" to suggest that someone should either know about the subject or do some research before answering a question. If it came across as "rude" then that's because I have already commented on the quality of Astromark's responses on other threads and yet he still continues to carry on posting answers to questions that he clearly knows little about. I don't think I can be blamed for being a little frustrated at that. I think it is perfectly justifiable to tell somebody that despite their obviously good intentions their answers and comments are not helpful if they do not know anything or know very little about the subject being discussed.

That is all I have to say about this situation. Now perhaps we could focus more on discussing stellar evolution here rather than looking for reasons to tear apart everything that I say and to assassinate my character.

EDG
2007-Sep-22, 11:22 PM
After further research, I have found a single paper that describes what I think Ken G is referring to as a "helium dwarf", and it is very clearly not what I am discussing in my article.

http://adsabs.harvard.edu/cgi-bin/bib_query?1987ApJ...322..842R

The mass of what this paper describes as the Helium Dwarf is estimated at less than 0.08 solar masses (not even massive enough to be called a proper star), and the method of its formation appears to involve a neutron star pulling off most of the mass of a former evolved giant star to reveal its helium core.

Again - if I have not already made it abundantly clear - this is NOT what I am referring to as a "helium dwarf" in my article (and I did deliberately put that name in quotes there, since I was unsure of any pre-existing proper name for the end result - that won't exist for billions of years - of the evolution of a low mass main sequence star).

I am having trouble believing that Ken G even read my article (or paid attention to what was said), because it is very clear from my description in there that I am not talking about the stripped helium cores of red giants formed in exceptionally unusual circumstances in binary systems. Maybe they are the same thing physically speaking, but their origins are very different and not what I was referring to. It therefore seems somewhat unreasonable for Ken G to accuse me of misleading people and making errors when I am not even discussing the stars that he is talking about.

Ken G
2007-Sep-23, 12:55 AM
I'm still waiting for you to show me an example of what I referred to as a "helium dwarf" (i.e. a solo, low mass star that has burned through all of its hydrogen).I am interested in the astronomical definition of a helium dwarf, as this is an astronomy forum. The fact is, the type of star that you are talking about, to wit a dwarf star that is primarily helium that is not fusing that helium, does not have to be a "solo" star. Evolution via mass transfer in binaries is a well known element of mainstream stellar evolution because such systems are not rare. Mass transfer has a way of emulating solo star evolution, but at a very different timescale, which is why helium dwarfs exist. All you need is for a star of roughly solarlike or more mass to evolve into a subgiant, in less then ten billions years, but in the process transfer its envelope to a nearby companion. Voila, you have a helium star that is not fusing that helium, just as you described, only more quickly-- so there is time to actually have them in our galaxy.


It would seem that you are referring to a different type of star that requires a very specific and rare set of circumstances to exist, and are erroneously claiming that today one can find (for example) a solo M V star that has reached the end of its natural evolution.
What I am referring to is the reason that helium dwarfs actually do exist. If you want to call a reasoning process that explains the existence of a real star as "erroneous", then maybe you should take another look at your own qualifications. and leave astromark's interpretation of language alone.
I wasn't in error though. It should be clear to anyone actually reading the article I wrote that it doesn't cover absolutely every possible situation that can come up in stellar evolution. What you just keep continuing to miss, is that I have no interest in your article on stellar evolution. I have interest in what a helium dwarf is, and why they exist in our galaxy. That seems like a more important criterion for inclusion in a Q&A section than debate about your web page.


What you're complaining about here is me talking about how unclear Astromark's phrasing of his question was.No, I'm complaining that you basically told astromark he shouldn't post here because his knowledge is insufficient to do so, but that's the role of the moderators. We all have insufficient knowledge, but we share what we can, and sometimes, as in your case here, we miss something pretty important and rely on others to correct us. astromark doesn't mind having that happen.


What you are referring to as "Helium Dwarfs" is evidently not what I am referring to as "Helium Dwarfs". You appear to be talking about white dwarfs igniting helium around them (or just to helium-rich white dwarfs), whereas I'm talking about the theoretical end point of low mass main sequence stellar evolution, where those stars have used up all their hydrogen. Both types of helium dwarf can occur from binary mass transfer. In the case of a helium dwarf nova, you're right that it would need to be a helium white dwarf. But you can get normal helium dwarfs in the manner I described above-- indeed, that's the only way you can get them, because as you point out, solo main-sequence evolution wouldn't have time.


Like I said, it should be clear to anyone with any reasonable skill in reading comprehension (and who has actually bothered to read my article) that it is clearly not a complete treatise on every single obscure aspect of stellar evolution, that it talks about solo stars only, and that I am just referring to those objects as "Helium Dwarfs" because I couldn't find a more appropriate name for them. As I once said already, the problem is not the incompleteness of your article, which is indeed an article about solo evolution and has no problems in my view. I wrote what the problem was above, did you "comprehend" what I wrote? Also, characterizing mass transfer in close binaries as an "obscure" form of stellar evolution is very inaccurate and could easily confuse perusers of this Q&A section, who may not know much about stellar evolution and rely on those with more knowledge to give them a fair interpretation of reality.

Tobin Dax
2007-Sep-23, 02:31 AM
Ken G is correct. Helium white dwarfs currently exist due to evolution from mass transfer. They are no different than the stellar remnants of low-mass MS stars. They are collapsed remnants of stars that, for whatever reason, don't have the mass turn burn past helium. These are the same types of stars that you're talking about. They may not be single stars that evolved to this stage without any external influence, but that doesn't change the fact that these are helium white dwarfs.


A couple more comments on the thread in general:

I didn't see this explicitly said yet, but once all the hydrogen turns into helium, they will collapse into white dwarf stars, supported by electron degeneracy pressure instead of radiation pressure.

I also am going to give a definition of an asymptote just in case somebody interested is still reading. An asymptote is basically a function whose value gets closer and closer to another value (i.e. zero), but never quite reaches it, even at infinity. 1/x is a good example of this. AGB stars have a path on H-R diagrams that is essentially asymptotic to the Giant Branch path.


Edit: Since I just went back and saw this comment, the Helium Dwarf Novae that you refer to, EDG_, are ingnition of accreted of H and He onto the surface of a helium white dwarf in a close binary system. These are the HeWD's that Ken G and I are talking about that are around now and the HeWD's that you're talking about that haven't evolved outside yet outside binary systems. To paraphrase, a helium white dwarf by any other evolution is still the remnant of a low-mass star that can't burn helium.

EDG
2007-Sep-23, 02:33 AM
I am interested in the astronomical definition of a helium dwarf, as this is an astronomy forum.

That's great. If you want to talk about that then why don't you do what anyone else would do and go start another thread about it and stop derailing this one.



Voila, you have a helium star that is not fusing that helium, just as you described, only more quickly-- so there is time to actually have them in our galaxy.

Again, that is not what is being discussed here. Astromark was asking about the stars I mentioned in my article - he was asking if any of "THESE STARS" were in our neighbourhood - he was not asking about the "stripped cores" that you're going on about.

You just blindly assumed that I was wrong to talk about one specific type of star (you know, the one being asked about) and then started lecturing me on how I was ignorant because I wasn't talking about other ways to form a Helium dwarf. Those other ways were not relevant for the purposes of the discussion that was actually happening - they're only relevant for the discussion you WANT to happen. And like I said, if you want that, go start another thread about it.



What I am referring to is the reason that helium dwarfs actually do exist.

I'm not arguing with that.



If you want to call a reasoning process that explains the existence of a real star as "erroneous", then maybe you should take another look at your own qualifications.

For a start, you can stop damn well patronising me. Unless perhaps you'd like me to suggest that you learn some basic reading comprehension before you start lecturing people about how they're wrong to talk about a specific type of star rather than the ones you're interested in.

The only way to form the star I was specifically talking about is by low-mass evolution. That is not "erroneous", that is entirely accurate for that specific instance. And that is all that is relevant to this discussion.

The "stripped cores" may be "helium dwarfs" as well but they are not the result of the evolution of low mass main sequence stars - instead they form when material is stripped from an evolved giant star to leave only its helium core behind (and not much of it at that). Those may be helium dwarfs from a physical perspective BUT THOSE ARE NOT WHAT WAS BEING DISCUSSED HERE AND ARE NOT RELEVANT TO THE QUESTION THAT WAS BEING ASKED.

If you wanted to say "he's right about the solo stars, but you can form helium dwarfs by other means, such as stripping off material from a giant star (such as example X)" then you could have just damn well said and all would have been fine - but instead you chose to patronise me and make out that I was wrong about what I was talking about when I wasn't, and here we are. It seems that you were more interested in trying to make an example of me than in trying to actually educate anyone.



What you just keep continuing to miss, is that I have no interest in your article on stellar evolution. I have interest in what a helium dwarf is, and why they exist in our galaxy. That seems like a more important criterion for inclusion in a Q&A section than debate about your web page.

Look, we were discussing something mentioned in the article I wrote on my webpage (and I'm beginning to wish I hadn't mentioned it now, since apparently it has to mention every situation a star can be in to be worth discussing. Clearly it's utterly useless). If you want to change the focus of the discussion or throw a strop because we're not talking about every conceivable instance that such a star can show up then that's your problem - but if you do, kindly have the decency to go start another thread to discuss it. That's how it works.

You're haranguing me because I answered a question that was actually asked, instead of explaining everything known about the subject - and that is patently ridiculous and completely unfair.



Both types of helium dwarf can occur from binary mass transfer. In the case of a helium dwarf nova, you're right that it would need to be a helium white dwarf. But you can get normal helium dwarfs in the manner I described above-- indeed, that's the only way you can get them, because as you point out, solo main-sequence evolution wouldn't have time.

That's great. If you could have said that to start with then that would have been much better. But that has nothing to do with what was actually being discussed. And oh look, you finally agree that I was correct about the main-sequence evolution aspect.



As I once said already, the problem is not the incompleteness of your article, which is indeed an article about solo evolution and has no problems in my view.

So with all due respect (which is very little right now), stop complaining. What I said in my article was what was being discussed, not the general principle of helium dwarfs and how they might form in any situation.



Also, characterizing mass transfer in close binaries as an "obscure" form of stellar evolution is very inaccurate and could easily confuse perusers of this Q&A section, who may not know much about stellar evolution and rely on those with more knowledge to give them a fair interpretation of reality.

I never claimed that mass transfer was obscure. What is obscure is that there are apparently only six known binary systems containing Helium Dwarfs. SIX. If that isn't obscure I don't know what is, and if you really think that it is worth making a point and arguing about stars that are that rare then you probably need to take a step back from the forums.

You've made your point, I acknowledge that there are other ways to form helium dwarfs (not that I ever denied it). Now kindly shut up about it.

neilzero
2007-Sep-23, 02:40 AM
Hi Ken G: Was that a typo 0.8 instead of 0.08? If not most class M and class K stars are not main sequence as all or most of them are between 0.08 and 0.8 solar mass. Does a K2 star have more mass than a K5 star? How archaic using romen numerals. How about a K zero star? Is it almost a G or almost an M? The EDG article link is a bit confusing. Neil

Ken G
2007-Sep-23, 02:45 AM
I didn't see this explicitly said yet, but once all the hydrogen turns into helium, they will collapse into white dwarf stars, supported by electron degeneracy pressure instead of radiation pressure.


Thanks for the clarification, and you are right, that point has not been made. I was more or less taking EDG_'s word for it that there was a class of helium star that could be about the size of a gas giant even though it was not burning helium, perhaps some sort of semi-degenerate solution that one might wish to distinguish from a white dwarf. I don't know if such a thing is possible or not, you are saying it isn't because without nuclear burning only degeneracy pressure can support a star. I was focusing on the fact that a star that is made of helium and is not fusing it can indeed be created in our galaxy, in contradiction to the implication of EDG_, and I value your corroboration on that.

(Minor nitpick: it is gas pressure that supports low-mass core-burning stars, not radiation pressure, but your point stands.)

Ken G
2007-Sep-23, 02:49 AM
Hi Ken G: Was that a typo 0.8 instead of 0.08? If not most class M and class K stars are not main sequence as all or most of them are between 0.08 and 0.8 solar mass. Does a K Vlll star have more mass than a K V star? How archaic using romen numerals. Neil

I think the mass limit for fusing helium is above 0.5 solar masses, but I'm just going on hearsay there, not astronomical papers. The 0.8 is the limit for stars to have evolved off the main sequence in the lifetime of the oldest stars, and 0.08, IIRC, is the limit below which you don't get fusion in the stellar core. I'm afraid I don't know what a K VIII star is, I don't know that many luminosity classes. Do you mean K8? If it's on the main sequence it would be a low-mass star but not as low as an M star, and if it is a type of white dwarf I'm not sure they can be seen that cold or even if any have had time to get that cold.

Ken G
2007-Sep-23, 03:19 AM
Those other ways were not relevant for the purposes of the discussion that was actually happening - they're only relevant for the discussion you WANT to happen.Actually, they are relevant to reality. This may be hard for you to believe, but the Q&A section is for questions about reality, not questions about your web page, and I assume that is the mindset most of its readers adopt.

For a start, you can stop damn well patronising me. So you feel it is fine for you to be wantonly patronizing of astromark, but cry foul when the shoe is on the other foot?


If you wanted to say "he's right about the solo stars, but you can form helium dwarfs by other means, such as stripping off material from a giant star (such as example X)" then you could have just damn well said and all would have been fineNo, all would not be fine-- because you could have done the same for astromark and chose not to. If you would look at my postings above, you will see that this was always my objection. Your erroneous implications about the impossibility of having helium dwarfs in our galaxy are a minor matter to clear up and indeed I would have cleared them up in precisely the way you suggest-- under normal circumstances.


It seems that you were more interested in trying to make an example of me than in trying to actually educate anyone. My goals were twofold: to educate you on double standards, while I also educated other readers about how it is actually possible to get helium dwarfs in reality. Otherwise, people might have had the same question as astromark:
Has this not happened some place we can see? Is that evidence that it might not ever actually happen that way.? So even when he was flat out asking if this might happen some other way, you failed to recognize that he was talking about the real objects, not your web page, and ultimately chided him that you had "obviously" (your word) already precluded the possibility that "such stars" could evolve in our galaxy. You see, for most people reading Q&A, "such stars" means real stars, not whatever specific mechanisms for arriving that them that you happened to be talking about on your web page.

I never claimed that mass transfer was obscure. What is obscure is that there are apparently only six known binary systems containing Helium Dwarfs. SIX.And how many helium dwarfs have been observed? Oh yeah, six. Remember, I didn't bring up this star-- I merely corrected you about how they get made, at this point in our universe, for those who care more about reality than discussing websites.

neilzero
2007-Sep-23, 04:00 AM
According to the link supplied by Stupendous Man, K zero is the hotest K type star with K1 and K2 being less hot, so K zero is almost a G9 star. Mass typically is proportional to main sequence color temperature, except our Sun was perhaps a G4 or G6 4.5 billion years ago, if we can believe the 70% or 75% cooler. In less than a billion years our Sun will be G1 temperature instead of the present G2. Have I got this correct?
I'm sure the greenhouse warming fans are delighted that astronomers think green house gases can more than make up for 25% less luminosity. Can we assume the luminosity was only 10% less in infrared, since the photographic plates likely were insensitive even in near infrared 120 years ago? Neil

Ken G
2007-Sep-23, 04:31 AM
According to the link supplied by Stupendous Man, K zero is the hotest K type star with K1 and K2 being less hot, so K zero is almost a G9 star. Mass typically is proportional to main sequence color temperature, except our Sun was perhaps a G4 or G6 4.5 billion years ago, if we can believe the 70% or 75% cooler. In less than a billion years our Sun will be G1 temperature instead of the present G2. Have I got this correct?That link seems dependable or he wouldn't have suggested it. I can't verify those numbers, but they seem fine.

I'm sure the greenhouse warming fans are delighted that astronomers think green house gases can more than make up for 25% less luminosity. Can we assume the luminosity was only 10% less in infrared, since the photographic plates likely were insensitive even in near infrared 120 years ago? I'm not sure what you're asking-- plates would not be a good way to infer the brightness of the Sun, and no significant changes in that brightness should have happened in 120 years. The proponents of the idea that we are seeing a brightening of the Sun are talking about much smaller increases. But you're right-- if models of the young Sun are correct, and we do have a pretty good track record there, then the Earth needed a lot of greenhouse effect or some such warming capability in its earlier days.

neilzero
2007-Sep-23, 05:50 AM
Up to about 65 years ago photographic film was insensitive to red light. We used red safe lights in the darkroom. Panchromatic film became popular and photo technicians had to develop in total darkness to avoid foging the film. If this was true of the plates used for astronomy, then even close M9 stars that humans can see would not appear on the early photographic plates. Perhaps this does not skew the color temperature analysis or they accounted for it.
I believe the CCD = charge coupled devices used with modern telescopes are better than the glass optics and atmosphere for reaching deep into the infrared, so we are finding M9 stars and brown dwarfs which we missed before.
Besides two meanings for helium stars, we have two very different kinds of white dwarfs. The A and F main sequence stars which are white and the resedue of a red giant after the fusion ends, which is tiny, extremely dense and blue, unless it has cooled for billions of years.
Since we believe stars with a mass about 1/5? that of of our sun and less have convection thoughout their radius, helium and hydrogen would be lost to a companion star about 50-50 % during the red giant stage, if such stars have a red giant stage. We may have to wait 100 billion more years before the first 1/5 solar mass star in our galaxy burns the last of it's core hydrogen, unless it looses much of it's mass to a companion star long before becoming a red giant. I suppose that is possible, but very rare. Neil

Neverfly
2007-Sep-23, 06:49 AM
I would like to address an issue that has become distracting and detracts from a discussion about something we all love- the stars.

EDG_ was, indeed, quite a bit rude to Astromark. Mfumbesi and I both jumped in and asked him to rethink it. Although EDG_ got defensive, he also seemed to simmer down and get back to good science.
He addressed all questions asked by all parties without being rude afterwards and I think that is commendable.

Astromark did, indeed, ask a question in post 33 (http://www.bautforum.com/1074009-post33.html) about it. EDG_
answered it in post 34 (http://www.bautforum.com/1074017-post34.html) and then Astromark asked it again right after (http://www.bautforum.com/1074019-post35.html) and EDG_ said he thought he was
clear in the first answer (http://www.bautforum.com/1074021-post36.html).

I had thought EDG_ was clear too and Astromark left me scratching my head on that one...:doh:
I don't believe EDG_ was rude in responding.
I believe that publically calling someone out, rather than in PM can be beneficial, but it's gotten to the point here of bickering.
Although EDG_ accepted my own challenge to him and did not retract his rude statements I do believe he got the point I was trying to make and his answers afterward were not anywhere nearly as insulting or rude.
Further discussion of it seems to run it into the ground and ruin the point and should I feel compelled to talk about it from this point onward Ill take it to PM.

EDG
2007-Sep-23, 08:00 AM
I was more or less taking EDG_'s word for it that there was a class of helium star that could be about the size of a gas giant even though it was not burning helium

That's funny, because I never even remotely said or implied anything of the sort. Are you sure you're even bothering to read anything I say, or are you so intent on trying to make me look bad that you're making stuff up now?

I said that I guessed a helium dwarf that had cooled down sufficiently might look like a big gas giant. Here:


(not sure what a Helium Dwarf would look like either - eventually I guess it'd look like a very big gas giant once it cooled enough).

Where you got that I had ever claimed that there was a type of helium dwarf "that was the size of a gas giant" is beyond me.

BigDon
2007-Sep-23, 08:04 AM
Neverfly, once again the voice of reason.

Okay, back on topic. I asked a largely ignored question here once about naked stellar cores. To wit, why don't they fluff up after they have their mantles stripped off? I thought it was the weight of the overlying materials that kept them compressed and as hot as they are. But this doesn't seem to be the case.

Trying to articulate a proper question I come up with, why doesn't a stellar core form a new mantle and a new smaller core? That would seem logical to me.

EDG
2007-Sep-23, 08:43 AM
I had thought EDG_ was clear too and Astromark left me scratching my head on that one...:doh:

Oh good, I'm glad someone here has a decent grasp of the english language.

I suppose it's lucky that I just accidentally deleted a response to Ken G that I was writing. At least it got most of the killing rage out of me. I probably would have got banned for a few days for it, but it would have made me feel better.

Things had settled down before Ken G butted in and started flinging his accusations around. His insistence that I was wrong (when I patently wasn't) and that I'd misunderstood what Astromark had said when he clearly (to anyone who can understand proper english) was referring to what I'd written, and his dismissal of what I'd written in my article and how it was not relevant to any discussion on this board is nothing less than rude, boorish, insulting, patronising, sanctimonious and offensive. And his pathetic attempts to "teach me about double standards" by insulting me and assassinating my character are rich coming from someone who is being as overbearing and obnoxious as he is. I am utterly disgusted that someone who is supposedly so educated would act in such a puerile manner. Doubtless he is proud of himself, and I'm sure he'll come up with some patronising response to this to get the last word in.

His sole motivation for derailing this thread was because he could not face the fact that someone was commenting on something I'd written. That's what all this was about really, and it's pathetic. Well thank you, Mr High and Mighty Scientist Who Thinks He Knows Better Than Everyone Else, I hope you're happy now that you've raised the tension and created lot more bad blood for the sake of your ego. Perhaps Ken should direct his clearly massive intellect on the fact that if he had actually engaged his brain before throwing his accusations to make his petty little point, we wouldn't have had several pages of arguing over something so stupid. Maybe he should take a look in the mirror sometime before accusing people of being overbearing and rude.

Fact is, Ken is a troll, no more and no less. He deliberately ratcheted up the tension levels because he thought he would "teach me a lesson", and he has singularly failed to do. I have said before in a previous encounter with him - he has nothing to say that I could possibly be interested in listening to, and even if he did he'd say it in a way that would just annoy the hell out of me. I just wish there was a more effective way to completely obliterate the posts that someone writes than a mere Ignore List.

Neverfly
2007-Sep-23, 09:06 AM
(snip) I just wish there was a more effective way to completely obliterate the posts that someone writes than a mere Ignore List.

I have found that once a party tries to understand the other- tensions cool down.

EDG
2007-Sep-23, 09:13 AM
I have found that once a party tries to understand the other- tensions cool down.

Ken is deliberately argumentative and obtuse - I've seen that in plenty of threads elsewhere that he "contributes" to. I will certainly not waste any more of my time on him - there will be no "understanding".

Neverfly
2007-Sep-23, 09:17 AM
Ken is deliberately argumentative and obtuse - I've seen that in plenty of threads elsewhere that he "contributes" to. I will certainly not waste any more of my time on him.

<chuckle>
Then do you have any ideas to respond to BigDons question?

I've thought up a few answers but don't wnat to say as I may get chastized for spouting nonsense:p

astromark
2007-Sep-23, 09:37 AM
And so they should...

Interestingly, I come to this forum because. Because I enjoy the discussion., but I stress that understanding and tolerance are rare here. That is a pity.
Tolerance of other points of view and proper explanation assist me in understanding some of the subjects I see here. Some of my questions are only to provoke answers from those who can best explain... So I continue...

Please feel free to help me understand this phenomena of the white dwarf. Its a star that has spent its hydrogen. Used up its mass to a point where it fails as a hydrogen conversion star... Its now comprising a greater content of helium and could if it had sufficient mass begin to convert that into what Iron? Carbon.?
I ask this question out of ignorance. I do not know. and want to.

EDG
2007-Sep-23, 09:51 AM
<chuckle>
Then do you have any ideas to respond to BigDons question?

I'm sure if I felt the effort to research an answer was worthwhile then I would, but I don't. Largely because I'm sick to death of this thread. I have been so put off trying to help people here that I am wondering if it's ever worth bothering to do so again in the future (perhaps it's the reek of Ken's urine as he marks his territory to fend off his competitors). I'm certainly not going to bother answering any of Astromark's questions again though, they are really not worth the hassle.

Neverfly
2007-Sep-23, 10:02 AM
Where's Whirlpool?!? EDG_ needs a hug!

BigDon
2007-Sep-23, 10:04 AM
Oh c'mon now EDG, this isn't worth self-destructing over. The mods will suspend you if you keep up the ad homs. You don't want to be lumped in with the clueless HB'ers who frizzle out 'cause they can't think their way out of a problem.

astromark
2007-Sep-23, 10:21 AM
I'm sure if I felt the effort to research an answer was worthwhile then I would, but I don't. Largely because I'm sick to death of this thread. I have been so put off trying to help people here that I am wondering if it's ever worth bothering to do so again in the future (perhaps it's the reek of Ken's urine as he marks his territory to fend off his competitors). I'm certainly not going to bother answering any of Astromark's questions again though, they are really not worth the hassle.

I will take this as a vialed appoligy... Its the closest thing to it I will get...and clearly is not one. How rude. You have now gone to fare EDG.
I would think a moderator should read this thread and do what is right here.

A question was asked way back at post 1. My contribution was not acceptable to you. Your response was blunt. And so on.... until now. You are what ... sorry? no... I think not.
My question goes unanswered from you. I am grief stricken:) and your attack on a valued contributor is unwarranted.
By the fact that we are in this discussion is itself enough to indicate a interest or passion for science over hear say. You may not like my manor as I find yours distasteful also. BUT I recognize your knowledge and respect your right to express your view here. Answer the question. Rise above the unkind thoughts...

EDG
2007-Sep-23, 10:44 AM
Oh c'mon now EDG, this isn't worth self-destructing over. The mods will suspend you if you keep up the ad homs. You don't want to be lumped in with the clueless HB'ers who frizzle out 'cause they can't think their way out of a problem.

Well, what's the point if someone like me who does have a proper scientific education and who genuinely knows a lot about the subject is just going to be harangued, bullied and insulted by career scientists for failing to answer a question that wasn't even asked?!. How pointlessly stupid is that, exactly? :doh:

Ken has spent the past few pages trying very hard to bully me into admitting that I'm erroneous about what I've said when I'm not (even though he later admitted that I was correct about what I did actually say). He's also tried to make out that I'm wilfully misleading people (which I'm certainly not) based on his own dubious interpretation of what Astromark was asking and on his "vision" of what he thinks the discussion should actually be instead of what people are actually asking about (while also deriding the quality of my article, which many people elsewhere with little background in stellar evolution have actually found to be a very useful introduction to the subject). That's not an "ad hom", that's a statement of fact - do you really just expect me to just sit back and accept that sort of treatment?

So it seems better for me to not attempt to answer anything if I'm just going to get that sort of hostility - and all this because I indicated how flawed and unhelpful Astromark's responses to the OP were (and regardless of how "nice" he is, the fact remains that his answers were incorrect. Maybe it was "blunt" but it was certainly justified). Though it's funny how people complained about me for coming down on Astromark there, and yet it seems nobody complained when Ken did the exact same thing to me in a far more offensive manner (and when I wasn't even wrong as well!). I'm starting to get the impression that some people feel that it's more important to "score points" here by beating down their peers than to actually educate people.

But like I said, the thread had got back on track before Ken barged in and turned it into a crusade to discredit me. I have an MSc in astrophysics and a PhD in planetary science, and I will not be intimidated by an intellectual thug.

Neverfly
2007-Sep-23, 10:57 AM
(snip)
So it seems better for me to not attempt to answer anything if I'm just going to get that sort of hostility - and all this because I indicated how flawed and unhelpful Astromark's responses to the OP were (and regardless of how "nice" he is, the fact remains that his answers were incorrect. Maybe it was "blunt" but it was certainly justified).
I jumped on your back for being a jerk about it.

Though it's funny how people complained about me for coming down on Astromark there, and yet it seems nobody complained when Ken did the exact same thing to me in a far more offensive manner.
http://www.bautforum.com/1075252-post65.html
Then I was supportive of your posts when Ken G was being a jerk.

I'm starting to get the impression that some people feel that it's more important to "score points" here by beating down their peers than to actually educate people.

But like I said, the thread had got back on track before Ken barged in and turned it into a crusade to discredit me. So I really don't know why I'm being painted as the bad guy.

Getting back on track may be just what it takes. In the meantime- Be the bigger man.

Everyone who has posted in this thread is guilty of jumping on someones back at some point.
Answering the questions scientifically may be what is needed to take care of the OP.

I for one have developed a lot of curiosity over a simple set of questions- especially with the large variance in answers.

BigDon
2007-Sep-23, 11:02 AM
Well, what can I say EDG? I, myself, had to quit posting here voluntarily for a about two weeks after another member twisted my words and finished thoughts for me and tried to make me look like a woman hater. Couldn't trust myself to be civil. Now I'm better.

Shoot take some time off. I did. you'll be better for it later.

BigDon
2007-Sep-23, 11:06 AM
Well, what can I say EDG? I, myself, had to quit posting here voluntarily for a about two weeks after another member twisted my words and finished thoughts for me and tried to make me look like a woman hater. Couldn't trust myself to be civil. Now I'm better.

Shoot take some time off. I did. you'll be better for it later.

EDG
2007-Sep-23, 11:06 AM
Answering the questions scientifically may be what is needed to take care of the OP.

The irony is that the OP was answered on the first page by myself and Tim.

Neverfly
2007-Sep-23, 11:09 AM
Well, what can I say EDG? I, myself, had to quit posting here voluntarily for a about two weeks after another member twisted my words and finished thoughts for me and tried to make me look like a woman hater. Couldn't trust myself to be civil. Now I'm better.

Shoot take some time off. I did. you'll be better for it later.

Same here. BAUT can be fun but sanity requires a break from it once in a while.

Neverfly
2007-Sep-23, 11:10 AM
The irony is that the OP was answered on the first page by myself and Tim.

Ok, well what about BigDons question?

Ken G
2007-Sep-23, 03:01 PM
I believe that publically calling someone out, rather than in PM can be beneficial, but it's gotten to the point here of bickering.I agree, all that needs to be said has been said, and science is all anyone wants to hear about now.

Although EDG_ accepted my own challenge to him and did not retract his rude statements I do believe he got the point I was trying to make and his answers afterward were not anywhere nearly as insulting or rude.

Since you mention it, I rather think it is a pretty low standard when people get kudos for being "less insulting and rude than before." Nothing less than an apology was remotely acceptable, in my view, but I'll leave the matter to the mods.

Ken G
2007-Sep-23, 03:05 PM
But like I said, the thread had got back on track before Ken barged in and turned it into a crusade to discredit me. I have an MSc in astrophysics and a PhD in planetary science, and I will not be intimidated by an intellectual thug.

Shall we then forget that the point I was actually making is that:
a) we do have helium dwarfs in our galaxy, and
b) they are formed via a very common mechanism: mass transfer in close binaries.
Now I feel we are on track on the subject of "are there any helium dwarfs in our galaxy".

Ken G
2007-Sep-23, 03:09 PM
I asked a largely ignored question here once about naked stellar cores. To wit, why don't they fluff up after they have their mantles stripped off? I thought it was the weight of the overlying materials that kept them compressed and as hot as they are. But this doesn't seem to be the case.
Back to science. You are right, stars do readjust when they lose their envelopes. But a lower mass star is generally smaller anyway, and when the core is held up by degeneracy pressure, it does not need to expand much to compensate for the loss of external compression-- it has a very high self-gravity when it is that small.


Trying to articulate a proper question I come up with, why doesn't a stellar core form a new mantle and a new smaller core? That would seem logical to me.
It is logical indeed, and that is pretty much what happens, but the new mantle is in many cases much smaller than the old one. The main point is, the star must satisfy its current governing equations, and you can usually ignore its history-- except insofar as that history establishes its main features like mass, composition, rotation, magnetic fields, etc.

EDG
2007-Sep-23, 06:56 PM
Nothing less than an apology was remotely acceptable, in my view, but I'll leave the matter to the mods.

You really need to get off your high horse, and stop lecturing people. If you're so concerned that people should be more polite and patient with people here, then proving the point by being vastly more rude and offensive than the original perpetrator is very hypocritical and unproductive, and just shows your true character. You owe me a huge apology for implying that I was wilfully misleading people. Your entire campaign against me has been based on your inability to understand basic english and on your obsession with answering a question that wasn't asked by anybody. You are entirely to blame for this situation, not me.

So if you want to preach about apologies, you can start by offering one to everybody here for starting a flameout because of your selfish attitude and trollish behaviour. Like I said though, I doubt that your motivations were to educate anyone in the first place - you just wanted to "teach me a lesson" and just feel threatened by other knowledgeable people disagreeing with you, you refuse to acknowledge that you've misunderstood the original questions and you've argued all this because you're blinded by your own agenda to prove how much better than everyone else that you are. For you it's a point of principle to prove your superior knowledge by undermining other people who are knowledgeable too.



Shall we then forget that the point I was actually making is that:

You mean the point that you have already admitted that you could have made without four pages laced with insults, barbs, and accusations - but didn't because you wanted to be a smug, holier-than-thou troll to "teach me a lesson"? Nobody's been made an example of here, and I'm sure everyone here is grateful to you for dragging a simple question into a four page flame war because you're too stubborn to admit that you were answering a question that nobody even asked in the first place.



b) they are formed via a very common mechanism: mass transfer in close binaries.

Here's another fact for you then: mass transfer in and of itself may be a common mechanism, but helium dwarfs are not even remotely very common themselves. In fact, they are so damn rare that they are hardly even worth discussing, and certainly not worth having a raging argument about. But again, all this flameage could have been avoided if you had ratcheted down your massive ego and just said this:

"Actually, in very rare cases of mass transfer in close binary systems it is possible to form helium dwarfs when the outer layers of a red giant are stripped away to reveal a helium core (such as the 4U 1820-30 binary, see reference (http://adsabs.harvard.edu/cgi-bin/bib_query?1987ApJ...322..842R))"

See? That would have been civil, educational, and would have caused no trouble at all. As it is you didn't even have the decency to point to any actual examples to prove the existence of what you were talking about - I was the one that had to dig around (quite deeply) to find that link, and it was the only mention of them that even explained what the "helium dwarf" was. But I guess you were so excited about trying to drag me through the mud that you forgot to cite an example of what you were talking about.



Now I feel we are on track on the subject of "are there any helium dwarfs in our galaxy".

That's great, but the point that repeatedly fails to penetrate your thick skull is that this wasn't the "track" that anyone (other than you) was on at all.

This thread really needs to die now (though I predict more "last words" from Ken as he continues to try to paint himself as the hero here). The OP was answered long ago, and you're still trying to foist the blame of its derailment onto other people when it was entirely your fault.

Paracelsus
2007-Sep-23, 07:27 PM
I'm sure the greenhouse warming fans are delighted that astronomers think green house gases can more than make up for 25% less luminosity.

Greenhouse warming fans?? Now there's a nasty little remark that came completely out of nowhere, had NOTHING to do with the topic being discussed herein, and is utterly childish to boot.

That remark also demonstrates how well-versed you are on the topics of AGW and climate science in general--not very.

Tobin Dax
2007-Sep-23, 07:28 PM
EDG, this is what happened in this thread:

1) Your very first post was an unfriendly-looking response to astromark that continued for the first page. The tone of your responses to Ken G has been similar to the tone of your initial posts.

2) In the post I quoted below, you were mistaken on two points.
-First was that we haven't seen any helium dwarfs. This is incorrect. This is what Ken G (and I) tried to point out to you, and you have conceded that HeWD's exist currently due to mass transfer. They may be rare, but they exist, we have found them, and we can study them. We know something about these stars, unlike you say in the quote below.
-Since you know a thing or two about stellar evolution, what do you think happens when stars stop fusing material in their core? They collapse. They have to. You claim otherwise. This is the point I really wanted to respond to in this thread. A tenth of a solar mass of helium is not in hydrostatic equilibrium if it's at the same density as it was when the star was fusing. Gravity takes over and it has to collapse. What did you mean when you said "it'd look like a very big gas giant"? That's a hard statement to parse, honestly. I was going to say this before I saw Ken G's responses. Would you have treated me in the same manner?

You made mistakes, and you were called on them. You didn't react kindly to that, and it didn't help that you also didn't react kindly to mistakes made by others. We all make mistakes. I did upthread, and I have an M.Sc. in astronomy, too. It happens. Relax, take a deep breath, don't take it personally, and walk away with some new knowledge.


I've not really found a good answer for that anywhere (possibly because it'd be tens of billions of years before we see one of these). It sounds as if the star's hydrogen just turns completely to helium and then it just sits there doing nothing else - the He can't be fused by the star, and I don't think it collapses, it just literally burns itself out. (not sure what a Helium Dwarf would look like either - eventually I guess it'd look like a very big gas giant once it cooled enough).

Neverfly
2007-Sep-23, 07:56 PM
Dude, did some passing Gypsie cast a curse on this thread that everyone responds to others posts with anger or what?!?!?!:doh:

ETA: Not you Tobin Dax.

EDG
2007-Sep-23, 08:05 PM
1) Your very first post was an unfriendly-looking response to astromark that continued for the first page. The tone of your responses to Ken G has been similar to the tone of your initial posts.

Well excuse me for defending myself against his attacks.


-First was that we haven't seen any helium dwarfs. This is incorrect.

No, it's not - that's the point that Ken keeps ignoring. The question -as phrased - was specifically about whether we had seen any helium dwarfs of the type that I was discussing on my webpage - i.e. helium dwarfs that formed as a result of the evolution of low mass stars that aren't in binary systems. That was what was being asked about given the context of the conversation. And I am entirely correct to say that they don't exist. There was no mention of any other types of helium dwarf in my article, so those weren't being asked about.



This is what Ken G (and I) tried to point out to you, and you have conceded that HeWD's exist currently due to mass transfer.

Right - but again, that is not what I was being asked about. And it took quite a while for anyone to even make it clear that the "stripped cores" are basically physically the same as the "end of low mass star evolution", even though they are the result of two very different processes.



-Since you know a thing or two about stellar evolution, what do you think happens when stars stop fusing material in their core? They collapse. They have to. You claim otherwise. This is the point I really wanted to respond to in this thread.

I didn't "claim otherwise". I think from the post you quoted by me it was pretty clear that I was unsure what they'd look like (and I meant to say thanks for clearing that up for me, but I forgot to do so in my defence against the barrage of Ken's attacks). I didn't realise that the star would collapse (into something resembling a white dwarf presumably?) if it was all helium, though it makes sense now that you mention it.



What did you mean when you said "it'd look like a very big gas giant"? That's a hard statement to parse, honestly.

Because I just thought it'd stop burning and then just cool down, kinda like a brown dwarf (those just cool down over time and eventually look like gas giants with clouds etc). So I guessed that the end result might be like a big (M V star-sized) helium-rich superjovian. But as I said, I made it obvious that I was unsure.



I was going to say this before I saw Ken G's responses. Would you have treated me in the same manner?

No, because you weren't being an arse about it.



You made mistakes, and you were called on them. You didn't react kindly to that, and it didn't help that you also didn't react kindly to mistakes made by others. We all make mistakes.

Except, like I said, I didn't make a mistake - I answered the question that was being asked of me correctly. I was responding to a question that looked very much to me as if it was being asked about what I was talking about in my webpage article. If Astromark was asking about helium dwarfs in general then he did not do so remotely clearly, which is hardly surprising as I have trouble enough deciphering his poor grammar and spelling at the best of times.

Even if I did make a mistake, I wouldn't take that personally. What I take personally are the accusations that Ken was throwing around and his claims that I was being "erroneous" when I wasn't.

As it is, the only things I have learned about this subject from this thread are what you said and what I've dug up on my own about it. If Ken wanted to impart any knowledge onto me himself then he has failed miserably.

Neverfly
2007-Sep-23, 08:09 PM
EDG_,
I sent you a PM. I hope you will consider that and look at this last post above and reconsider it.
lets discuss science- Not eachother...

ETA: Sitting here on the outside, I will say it bluntly.
Yes you made a mistake. In fact you made several. Step up and recognize- take a moment and think about it- Then work toward correcting it.
It's perfectly ok- I WISH I had a penny for every mistake I made in life and A $1,000 for each one that I admitted to and addressed.

ETA Rnd 2: I for one would like this thread to continue and progress so I can know a thing or two about Stellar Evolution too;)

EDG
2007-Sep-23, 08:31 PM
ETA: Sitting here on the outside, I will say it bluntly.
Yes you made a mistake. In fact you made several.

You can think what you like, but I'm pretty damn clear that I didn't. Maybe you guys are more skilled at deciphering what Astromark really means when he asks something in his broken english than I am, I dunno... but from what he actually asked (which is all I have to go on) - no, I answered exactly the question that he asked, and I answered it correctly. I was then dragged through the dirt because I didn't answer a question that he didn't ask, and that is ridiculous. That is the end of the matter - if you want to discuss stellar evolution then go right ahead and stop commenting on what I or anyone else said.

Meanwhile, I'm out of here - I'm fed up with this treatment. Maybe I'll be back, but I suspect that would largely depend on whether Ken G decides to either stop posting or stop being so obnoxious.

Tobin Dax
2007-Sep-23, 08:50 PM
Dude, did some passing Gypsie cast a curse on this thread that everyone responds to others posts with anger or what?!?!?!:doh:

ETA: Not you Tobin Dax.
Darn it. I gotta work on casting curses, I guess. ;)


Well excuse me for defending myself against his attacks.
He attacked you before you posted in the thread? :confused:

EDG
2007-Sep-23, 09:20 PM
He attacked you before you posted in the thread? :confused:

I've had run-ins with him before here, and he came across just as sanctimonious and obnoxious as he's done here.

Before I go, let me just break down Astromark's initial post that started all this trouble (#33):


Why so long before we see one of these?

In the context of the conversation at the time, "these" clearly is referring to the stars that I mention in my article - the low-mass evolution end-points that I refer to as "helium dwarfs". I correctly replied that it takes so long because the low mass stars are so long-lived.



Has this not happened some place we can see?

Here, "this" again refers to "the formation of helium dwarfs as a result of low mass evolution", since that is the only thing being discussed at this point. Again, I answered correctly that it hasn't, again because those low mass stars haven't had the time to evolve that far yet.



Is that evidence that it might not ever actually happen that way.?

I have difficultly parsing the question given Astromark's poor grasp of english grammar. While I didn't answer this directly, the lack of any helium dwarfs formed as a result of low-mass evolution is not evidence that helium dwarfs cannot form in any other way, and I have never claimed that low mass evolution was the only way they could form.

In post 35, Astromark then asked:


wow... thx, Thats stability.
but, seriously are there any of these in our observable area.. ?

Again, "these" is clearly referring to the helium dwarfs formed as a result of the evolution of low mass stars, because those were the only type of "helium dwarf" being discussed up to that point.

Ken then "called me to task" in post 45 by making vague references (without cites) to helium dwarfs and helium dwarf novae, to which I responded (truthfully) in post 47 that I had never said that there weren't other ways to form those stars and said that anyone was welcome to explain any alternative formation methods. In post 49 I asked for citations to evidence that the stars that Ken claimed to exist did actually exist. I received no evidence, and I eventually had to find a reference myself after much searching,

Then in post 50 Ken started lecturing me about how erroneous I was and about my "rudeness" and it all devolved from there.

So again - I was correct in all the responses I made to the questions that were actually being asked. I interpreted Astromark's ambiguous question (in post 33) as "is the lack of helium dwarfs formed as the result of the evolution of low-mass stars evidence that they cannot be formed in any other way", and while I did not directly respond to that at the time (which if anything is an omission not an "error"), if I were to answer the question again based on what I knew at the time then the answer I would give to that is "no, it is not evidence that helium dwarfs cannot be formed in any other way, but I don't personally know of any other ways in which they can form".

Either way, he never actually asked "how would a helium dwarf form if it didn't form as a result of low mass stellar evolution?", or even "are there other ways in which helium dwarfs can form?", which is the question that Ken G is accusing me of being "erroneous" about. Meanwhile, I was correct in my responses to all his the other questions - at worst my only crime is not directly answering one of them that was poorly phrased to start with, but that certainly isn't an "error".

Does that make my stance crystal clear?

Neverfly
2007-Sep-23, 09:31 PM
Not really.
For one thing you left out your hot posts to Astromark Previous to post 33.

Fuel for the fire. Agreed it IS past but since you feel compelled to dredge up the past- a past you did not admit to being wrong to either- we may as well dredge it all up.
Agreed that KenG was as rude to you as you were to Astromark. Agreed it got annoying. It severly detracted from the thread as well.

You called others on what they said. You, too, have been called on what you said. Ken G is currently not around.
However, you cannot change a person. Nor can you control any person. But there IS one person you CAN. Yourself.
Now you can go around blaming EVERYONE else
Or
You can look to yourself.

"Go to your bosom: Knock there, and ask your heart what it doth know." -- William Shakespeare
So far EDG_ you are showing a complete inability to correct yourself in spite of your wanton correcting of others.

ETA: In spite of my earlier statement that I would state my case in PM, I have resorted to posting it in here since all PM's to EDG_ have gone unanswered.

ETA numbah too: Tobin Dax pointed out where you were wrong in some areas too.
Tobin Dax jumped on MY back several months ago when I was wrong and wouldn't recognize it. I needed a swift kick in the butt and this was one of several people who delivered it.
A swift kick in the butt sometimes is just what a person needs to get moving again.

Neverfly
2007-Sep-23, 09:36 PM
In spite of the defensiveness going on..


Can ANYONE ELSE answer Mine and BigDons as well as the OP's questions?
With all the bickering I've lost clarity here.

I'd really rather see logic and science win over emotions in this thread so we can all have the answers we originally, simply just wanted <shrug>

EDG
2007-Sep-23, 09:48 PM
Not really.

Then I suggest you read it again. Because I'm crystal clear about it.



For one thing you left out your hot posts to Astromark Previous to post 33.

The "hotness" of my responses isn't the issue. The issue is that I've been accused of misleading people and being erroneous about things that I haven't been erroneous about, and I just demonstrated exactly why those are false accusations.



You called others on what they said. You, too, have been called on what you said.

And I believe have successfully defended myself against those accusations.



Now you can go around blaming EVERYONE else
Or
You can look to yourself.

Given that I have just demonstrated precisely that I am not to blame here, I'm happy to continue blaming others for causing this firestorm.



So far EDG_ you are showing a complete inability to correct yourself in spite of your wanton correcting of others.

Despite your accusation, I have actually admitted that I was mistaken about a few details (such as what the mass limit was for helium dwarfs to form through evolution, or what a helium dwarf would look like) - because I was actually mistaken about those. Everything else I've been correct about, as I have just shown - so I am certainly not going to "correct myself" when I know I'm already correct.



ETA: In spite of my earlier statement that I would state my case in PM, I have resorted to posting it in here since all PM's to EDG_ have gone unanswered.

That would be because you are on my ignore list.



ETA numbah too: Tobin Dax pointed out where you were wrong in some areas too.

Right, and I accepted that I was mistaken about the aspects that he pointed out. What's your point?

I've made my case very very clearly here. I have been attacked for not answering a question that nobody asked at all, and I am not going to admit I am wrong to not answer it because I was categorically not wrong about it. Now, if you genuinely want to talk about stellar evolution you will stop pressing the point and wait for an answer to your evolution questions from someone who cares enough to post.

Tobin Dax
2007-Sep-23, 10:33 PM
In spite of the defensiveness going on..


Can ANYONE ELSE answer Mine and BigDons as well as the OP's questions?
With all the bickering I've lost clarity here.

I'd really rather see logic and science win over emotions in this thread so we can all have the answers we originally, simply just wanted <shrug>

What questions haven't been answered? Ken answered Don's (though I could restate the answer in less-jargony terms if he wants), and I don't see an unanswered question of yours.

BigDon
2007-Sep-23, 10:50 PM
Hey, I'm good.

Neverfly
2007-Sep-23, 11:39 PM
What questions haven't been answered? Ken answered Don's (though I could restate the answer in less-jargony terms if he wants), and I don't see an unanswered question of yours.

You're right. I forgot to ask mine..
And now I can't even remember what it was. Ugh.
I diidn't get to the part in Ken G's posts that answered BigDons as his provoking and antagonising of EDG_ annoyed me more than the posts were worth to read..

Neverfly
2007-Sep-23, 11:48 PM
EDG_, Drink a Dr Pepper. Relax. Read the "Stop Posting Mystery Links Please " thread in About BAUT.
IT DEMONSTRATES a time when I was blissfully unaware of where I was mistaken and had "defended" and "justified" my stance.
I was mistaken though.
I acted like Donald Duck instead of Henry Kissinger.
I took a trivial issue and assigned to it all my grievances about BAUT.
And most of all, I wouldn't listen to others trying to reason with me.
In fact, I still say I was RIGHT about a lot of what I said. It was my delivery that was all wrong.
THAT is why I can see with "crystal clarity" where it is you are mistaken.
Now I'm asking you to review, read your PM's and think about it.

I don't know if it will do any good. Maybe only a Mod delivering a threat will get through to any of us.

But if there is ONE thing BAUT consistantly teaches me:
How to communicate and look at my own mistakes before looking at anothers. Once I have addressed my own- then I can address others.
You are failing to see that it wasn't really the facts and information where you were wrong- but your hostile defensive attitude and aggressiveness in dealing with folks that are trying to help you see more clearly.
Now poor m1omg had his thread ruined because a few grown adults acted like kids while the young ones on this board acted like adults.
Please don't disect this post too. Just think about it- and PM me the results- Or don't respond eh? I wouldn't bother posting yet again except that I haven't quite given up on you yet.

Ken G
2007-Sep-24, 01:14 AM
If you're so concerned that people should be more polite and patient with people here, then proving the point by being vastly more rude and offensive than the original perpetrator is very hypocritical and unproductive, and just shows your true character.The problem with the logical content of this argument is that if you look again at my posts, I think you will find that not a single critical thing I said was not taken directly from your mouth. I introduced no new vocabulary into the discussion, and indeed I ignored many of yours. How that adds up to "vastly more rude" is beyond me. (Note that once I again I merely take you to task for your own words, which is all I have ever done here.)


You owe me a huge apology for implying that I was wilfully misleading people. No, I don't owe you an apology for that, as nothing I said implied willfullness (a matter of obvious record), and mislead is just what you did (as clearly demonstrated by Tobin Dax). But that's no big deal, we all mislead by accident when we make a mistake. The big deal was your tone, and all your very own words I turned back on you and made you go ballistic, as if no one else had the right to do that to those very same words! (Remember, I let you bring in all the words, and all the tone.) What I owe you an apology for was calling you out on your own bad behavior. As such, my own behavior was also bad, and I will happily apologize to you-- as soon as you do so to astromark.


You mean the point that you have already admitted that you could have made without four pages laced with insults, barbs, and accusations - Again, I challenge you to find a single "insult, barb, or accusation" that you did not bring into this thread first. I never did anything but apply your own words to you, and I'm sorry if you think that's unfair.


Here's another fact for you then: mass transfer in and of itself may be a common mechanism, but helium dwarfs are not even remotely very common themselves. The issue I clearly described is not how rare they are, it is how they are made. For people interested in this interesting yet rare class of star, that's what they'd want to know. In fact kudos go to you for even bringing up this class, by linking to your web page, it isn't widely known yet has a lot to say about stellar interiors.


That would have been civil, educational, and would have caused no trouble at all.Absolutely correct, and is exactly what I would have done under normal circumstances. All the rest you brought onto yourself-- the shoe on the other foot, pure and simple.
But I guess you were so excited about trying to drag me through the mud that you forgot to cite an example of what you were talking about.
Citing examples is an excellent, though not strictly necessary, component of discussing a type of star, you are right. I am in your debt for finding them, there's never any substitute for real research into a topic.

That's great, but the point that repeatedly fails to penetrate your thick skull is that this wasn't the "track" that anyone (other than you) was on at all. Again, in my view discussion of real stars should include how said real stars are actually made-- if you view that as a "strange track", I can't agree. Didn't you just get through claiming that my posts were "more rude and offensive" than yours? I find the logical inconsistencies in your appeal somewhat bizarre.

Neverfly
2007-Sep-24, 01:16 AM
:wall:
http://www.cosgan.de/images/smilie/konfus/a080.gif
KenG.. Let me just say as one who has not gone toe to toe with you yet...

Your posts were just as bad as EDG_'s were. You are both equally guilty of a peeing for distance contest.
The more you keep replying to eachother- the more distance each is going to aim for.
Would one of you PLEASE accept personal responsibility for your OWN actions and offer, if not a manly apology, at least a truce?
This poor thread is so beat up the Suns mini black holes are now large Black Eyes.
In fact The sun has more shiners now than it has in 4 billion years :mad:

First one to step up gets the Dr. Pepper.

Ken G
2007-Sep-24, 01:38 AM
Your posts were just as bad as EDG_'s were. You are both equally guilty of a peeing for distance contest.You're right, but I did it for a reason-- to put the shoe on the other foot. What's his excuse? (Furthermore, I think even a cursory examination of the language used would make it a tough case that we are "equally guilty", but your main point is that nobody really cares to establish "levels of offensiveness" here-- any step over the line of polite discourse is a step over that line.)
First one to step up gets the Dr. Pepper.

All right, I was going to wait for an apology to astromark by EDG_, as I think astromark might actually appreciate that (he's the only real victim in all this, certainly not EDG_ despite his posturing as such) but I guess it's pretty apparent that isn't going to happen. But you have pointed out the fact that the other victim is the thread itself-- and the readers of it who had no interest in that exchange but were interested in stars. For everyone who had to painfully wade through that exchange, including yourself, I do apologize. I guess it just seemed important to not only answer astromark's question about whether or not we see helium dwarfs and how they are made, but also to make a certain individual see the error in their ways. They are seemingly not capable of it, but I am, so I can recognize that I was wrong to derail the thread, and I apologize. To you. If EDG_ wants my apology too, he knows what it will take. I do not plan to post again to this thread unless that happens.

EDG
2007-Sep-24, 01:42 AM
I'll say just one thing in response to Ken. Since he's so concerned about this board being a place for general Questions and Answers about astronomy, can he perhaps explain to everyone why he chose this board as a venue for performing psychological/social experiments on other posters? It isn't even remotely his place to "turn anyone's words against them" to teach them a lesson, and if he wanted to do that then he should have done so in private. If he was that concerned about my tone then he should have reported my post to a moderator. Instead, he took it into his own hands, derailed a thread, and started a flamewar, because "it seemed important". He stepped way over the line to make a point that wasn't even relevant to anything.

Very "responsible" of you, Ken.

I will apologise to everyone else who had to wade through this debacle, but the blame for it lies squarely with Ken. I will certainly never apologise to Ken for anything I have said to him, and I will not apologise to Astromark for pointing out how wrong he was (again). He seriously needs to learn to check his facts before he posts and to tidy up his grammar and spelling enough that his posts are unambiguous in their meaning. I acknowledge that I was short and impatient with Astromark, but I will not apologise for that. I have shown in post #95 that I answered the questions that were actually posed to me by Astromark correctly, and there is nothing more that I could have done than that. I have admitted where I was mistaken about details when they were pointed out by Tobin Dax. Beyond that, I have done nothing wrong. All I have done here is stood my ground against Ken's intellectual bullying and sanctimonious thuggery, and I will apologise to nobody for doing that.

kashi
2007-Sep-24, 02:06 AM
Put yourself in the situation of someone who googled "sun's evolution" and found this page of this thread. I doubt they'd spend more than 5 seconds before closing the tab or clicking back.

If you're going to argue, argue about the science, not about the nature of argument itself. Criticize the reasoning, not the person!

astromark
2007-Sep-24, 07:52 AM
:)...Its me, I'm back... run for your lives...

No, not fair EDG. You have been unfair to me. I do not want to reduce this thread to this.. so no I will not go on about it... but,

It is apparent that I have not a BSc or any of your higher education certificates. My grammar is out of kilter with some. My spelling has its own agenda.... Well, get over it. I will not be changing any day soon. BUT for sending this thread to hell I am SORRY. I will make the effort to be understood...some how. Please show me a little tolerance. I may not be the brightest candle on the cake, but I do want to know. That is why I asked... No malicious intent intended. so now I will ask what I see as the questions that I want answered from this thread. If they look new to you then yipee... I have achieved a goal. Been understood.:)

1/ So as I might learn more about these stars that are not so massive as to colapse... at the end of the hydrogen cycle. where do I look to find a candidate for this.. Not our sun as its the wrong type and size.
Yes EDG I have read your article and understood you well. I know I can not see a white dwarf ( other than the ones that have been part of pairs )...
I wanted to know where can I actually observe a candidate star.
These are not brown dwarfs but white ones... I understand a low mass star can be very long lived. Is that right?
Are the energies expelled less energetic. Does that sagest long evolution periods ? Would these be good candidates for a civilization. Yes understanding the fact of planets at the sweat zone.. but lets not derail this post completely. I never intended to Trojan horse this line of thought.

Neverfly
2007-Sep-24, 08:08 AM
This is a paper from Harverd. (http://adsabs.harvard.edu/abs/2000MNRAS.317..952A)
It's a bit technical and some math but even just reading the article is very informative.
As far as location of one- I dunno- bigger brain needed to come up and post on that.

You said something about planets for a civilization?
Do you mean human or alien? If alien, there is no way of knowing what kind of environment or conditions a hypothetical alien developed in. That kind of speculation without any knowledge would be best left to day dreams...
I wondered about the thoughts in the OP's head when he asked the question...
Was it because someday Humanity will need to take to the stars?

astromark
2007-Sep-24, 08:19 AM
Thx for the link... good.
Not really wanting to go into alien descusion... just the stability question regarding a habitat that remains stable must be a life friendly environment. I was daydreaming about building environments around stable stars. For us.

ToSeek
2007-Sep-24, 02:46 PM
I think this thread is an object lesson in why we have a rule (that perhaps needs to be more explicit) about trying to police this forum yourself rather than reporting issues to a moderator. (See Rule 16: "Do not talk about bad posts in the forum itself...". This goes for EDG_ complaining about Astromark and then everyone after that who complained about EDG_. All of you should consider yourselves formally warned. (And if you're not sure it applies to you, then it does. PM me if you really want a clarification.)

I was going to try to go through this thread to pull out the irrelevant, bickering posts and just leave the science, but they're so intertwined that that would be very difficult. Plus I think it would be nice to leave this here as an example of how not to handle a situation.

ToSeek
BAUT Forum moderator

Ken G
2007-Sep-24, 03:01 PM
Point taken-- compounding an error is never a way to solve it. I will respect Rule 16.

John Mendenhall
2007-Sep-24, 05:24 PM
:)...My spelling has its own agenda...

Loved it, Astromark. Funniest thing I've read in a while. I've always enjoyed your posts and those of the rest of the posters on this thread, also. The thread just wandered off in the wrong direction. One thing BAUT is good at is teaching tolerance; I'm a twit for spelling and grammar, but BAUT has taught me to just let it ride, as long as the meaning is clear. It's like that old joke quote from the newly graduated engineer: "I always wanted to be an engineer, and now I are one."

neilzero
2007-Sep-24, 05:28 PM
Hi astromark. You are correct: Our Sun will collapse into a very compact white dwarf in 4 billion years, perhaps 6 or 8 billion years. Stars with less than 10% of the mass of our Sun (perhaps 50%) will shrink (to not much bigger than Jupiter) slowly as they cool after they have converted their hydrogen to helium. We don't think any have done this yet, as these stars have only converted a small percentage of their hydrogen to helium. Yes, the energies expeled are less energetic. Estimates run up to a trillion year supply of fissionable hydrogen. Centauri Proxima and Barnard's Star are two nearby stars of this type. A planet close enough to have liquid water would likely keep one face toward it's red sun, so inhabitants would need artifical light to see colors other than red and black. Unless the atmosphere was thick and had greenhouse gases, most of the water would be trapped in a giant glacier on the dark side. If the low mass star had a companion that came close, part of the great ice cap would melt and evaporate. Centuri Proxima (sometimes called Centauri C) has two larger companions almost as massive as our Sun, but we don't think either will ever get close enough to melt ice near Centauri Proxima.
The nearest known white dwarf is a companion to the brightest star, Sirus. It is visable with a modest telescope. Other white dwarfs may be even closer. They are difficult, but not impossible to find with a very powerful telescope, with or without a companion. We may find one as part of our search for very dim asteroids and comets. They will likely be blue, except they are typically too dim to determine the color. A planet near a white dwarf would be bathed in deadly Xrays and ultraviolet light, but not enough infrared light. Neil

astromark
2007-Sep-24, 07:42 PM
:) Great joy... I have been understood and answered.. YES! and Thank you all.