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Thread: Sun's evolution

  1. #1
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    Sun's evolution

    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?

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    Quote Originally Posted by m1omg View Post
    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.

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    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.
    Last edited by astromark; 2007-Sep-18 at 07:23 PM. Reason: gramer

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    Lightbulb Final Destiny

    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 of solar evolution. See my article "Final Destiny" in the newsletter of the Los Angeles Astronomical Society, April 2007 issue, for a better time line & explanation.

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    Quote Originally Posted by astromark View Post
    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.
    Last edited by EDG; 2007-Sep-19 at 01:13 AM.

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    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.

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    Quote Originally Posted by astromark View Post
    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.

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    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.

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    good grief.

    Quote Originally Posted by m1omg View Post
    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.

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    Quote Originally Posted by mfumbesi View Post
    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?

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    Quote Originally Posted by astromark View Post
    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.
    Last edited by EDG; 2007-Sep-19 at 10:21 PM.

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    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.

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    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).

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    Quote Originally Posted by Neverfly View Post
    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.
    Last edited by EDG; 2007-Sep-20 at 04:24 PM.

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    Quote Originally Posted by EDG_ View Post
    Really now. I've provided answers to the OP's questions. What have you done?
    Childish and irrelevent response.
    Quote Originally Posted by EDG_ View Post
    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.
    Quote Originally Posted by EDG_ View Post
    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.

    Quote Originally Posted by EDG_ View Post
    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.

    Quote Originally Posted by EDG_ View Post
    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.

    Quote Originally Posted by EDG_ View Post
    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.

    Quote Originally Posted by EDG_ View Post
    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.

    Quote Originally Posted by EDG_ View Post
    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.
    Quote Originally Posted by EDG_ View Post
    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.
    Quote Originally Posted by EDG_ View Post
    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.

    Quote Originally Posted by EDG_ View Post
    I think it says a lot more about you
    Irrelevent.
    Quote Originally Posted by EDG_ View Post
    that you feel threatened by someone
    I don't feel threatened. Vague assumption. There's not need to boost your ego. Get over yourself.
    Quote Originally Posted by EDG_ View Post
    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.
    Quote Originally Posted by EDG_ View Post
    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.
    Quote Originally Posted by EDG_ View Post
    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.
    Quote Originally Posted by EDG_ View Post
    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.

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    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.

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    Quote Originally Posted by EDG_ View Post
    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."


    Quote Originally Posted by EDG_ View Post
    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.

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    Quote Originally Posted by astromark View Post
    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.!

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    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.

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    Quote Originally Posted by Tim Thompson View Post
    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 of solar evolution. See my article "Final Destiny" in the newsletter of the Los Angeles Astronomical Society, 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.

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    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?

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    Quote Originally Posted by astromark View Post
    (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.

  24. #24
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    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"
    Time wasted having fun is not time wasted - Lennon
    (John, not the other one.)

  25. #25
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    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

  26. #26
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    Quote Originally Posted by Neverfly View Post
    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.
    Time wasted having fun is not time wasted - Lennon
    (John, not the other one.)

  27. #27
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    Quote Originally Posted by BigDon View Post
    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
    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.

  28. #28
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    Quote Originally Posted by Paracelsus View Post
    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 for the layman (doesn't cover everything, but it covers the basics). So you might find that useful.

  29. #29
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    Quote Originally Posted by BigDon View Post
    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/Teach...Evolution.html

  30. #30
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    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?
    Time wasted having fun is not time wasted - Lennon
    (John, not the other one.)

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