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Littlemews
2003-Nov-26, 04:43 AM
5 billion yrs later, yea 5 billion yrs later, the sun use up its energy and become White Drawft...hmm then is this the end of human race? We cant live on Jupiter or other Jovian planets right? So any good idea about where we, human can live?

eggplant
2003-Nov-26, 06:14 AM
in 5 million years we'll either be spread all over the galaxy like Los Angeles in the desert , or long since self destructed... But it is something to think about... At least that's what I think ;)

Haglund
2003-Nov-26, 09:08 AM
I agree, after 5 billion years the world, and us, will be very different from now. Maybe our civilization will still be around by then, but it is nearly impossible to imagine how we would have evolved. Would we still be biological beings? If so, how would we have evolved? The thing is, 5 billion years is longer than there's been life on this planet, and Homo Sapiens have been around for about a blink of an eye, if we look at the big picture. In a million years maybe we will not be "Homo Sapiens" anymore. Also there is the thing with technology and how that would have an effect on the natural biological evolution. Will we change all that? Will we decide the course of, and speed up, our "evolution"? It's impossible to know how things will be 5 billion years ago, but I'm guessing that if the same intelligence that arose in Africa some million of years ago will exist in an unbroken 5 billion year chain, "we" will have spread out over large portions of this galaxy and probably other galaxies as well. 5 billion years is a long, long time...

QJones
2003-Nov-28, 12:51 AM
5 billion years is a long, long, LONG time.

It's one of those things I don't worry about.

Here's an example. If you continue with the current growth rate (assuming we could, we don't need a discussion that 'things change in the future') of 1.1% per year (or a doubling time of about 50 years), then in 5 billion years we'd have

S=P(1 + 1.1%)^n

S= 5,000,000,000people(1.011)^5000000000years

S= breaks my computer's calculator.

trekgoddess
2003-Nov-28, 02:42 AM
Well if you had started at the beginning of the human existence and gone by reproduction rate there would be WWAAAAAAAAAAAYYYYYYYYYYY more humans today, but fortunetly we have sliced the world population in half many times. Killing other people is one of mankind's greatest achievements, from a certain point of view, for we have been doing it so long that it has become almost instictual. So, ya think the sun is going to be a problem? It is more likely that I will destroy the human race than our sun will. Oh and if you want a list of the five most plausable ways scientists have come up with that we will kill ourselves here it is, because right now I'm thankful we haven't (Thanksgiving pun intended).
1)Nuclear Holecost-only reason nukes haven't been used yet
2)Virus/Bacteria wipeout-ebola anyone?
3)Global Warming-not fast but it will probally hurt us a lot more than it did Kevin Cosner's career
4)Asteroid-even if it does hit Paris kaboom
5)Earthquake/Volcano-RING OF FIRE!!!!!!!

Planetwatcher
2003-Nov-28, 02:55 AM
I will be long since gone so I'm not going to worry about it.

DippyHippy
2003-Nov-29, 01:47 AM
:rolleyes: Typical Planetwatcher... it's always self self self with you, isn't it? LOL (Joke!!!!)

Dave Mitsky
2003-Dec-01, 12:24 PM
Originally posted by trekgoddess@Nov 28 2003, 02:42 AM

1)Nuclear Holecost-only reason nukes haven't been used yet


The people who died at Hiroshima and Nagasaki would most likely be surprised to hear that, if they were in a position to hear anything that is.

Dave Mitsky

Littlemews
2003-Dec-01, 08:12 PM
Originally posted by Planetwatcher@Nov 28 2003, 02:55 AM
I will be long since gone so I'm not going to worry about it.
Let said, not the death of the sun, but the Earth ^^, even earth has its death...so if the core use up its fusion, then what will happen to us? No air, no gravity, no atmosphere????

Whim
2003-Dec-02, 03:17 AM
The fusion provides some heat to the earths surface, but it is insignificant compared to the solar heat we get. As far as the atmosphere and gravity are concerned, the total particle count, before, and after the fusion stops, will be about the same. Thus the gravity that holds us and the atmosphere to the earth will remain about the same.

One thing that would affect us is the lack of heat from the fusion that now keeps the earths core melted. If our theories about the magnetic field surrounding the earth are correct, this field would disappear with the core becoming cool. This field is what provides the most protection to us from the charged particles coming at us from all directions in space. We most likely could not survive without this magnetic field.

damienpaul
2003-Dec-20, 03:55 PM
There is a brilliant article in the New Scientist magazine of the 6th December 2003, entitled Earth's future. they mention - Silicon Snow, Iron rain and an Argon Ice cap...

I would be very interested in hearing other members' views on this article.

Whim
2003-Dec-21, 05:23 AM
Oh how it hurts. Here I try to sound something like an educated person and I use "fusion" in place of "Fission". Sorry about that. The heat in the earth's interior is primarily from FISSION, radioactive decay, not fusion!

damienpaul
2003-Dec-21, 05:55 AM
don't worry about it mate, I was figuring you meant that.....still sound intelligent!

Littlemews
2003-Dec-22, 05:39 AM
Originally posted by damienpaul@Dec 20 2003, 03:55 PM
There is a brilliant article in the New Scientist magazine of the 6th December 2003, entitled Earth's future. they mention - Silicon Snow, Iron rain and an Argon Ice cap...

I would be very interested in hearing other members' views on this article.
And Lava Rain ;)

damienpaul
2003-Dec-22, 05:43 AM
thats the one!!! what is your view on that article?

kashi
2003-Dec-22, 01:38 PM
Is that article publihed online? A URL would be great!

damienpaul
2003-Dec-22, 04:28 PM
i am not actually sure, but i'll check for you

Planetwatcher
2003-Dec-22, 07:36 PM
Posted on Dec 1 2003, 08:12 PM
I'll still be long since gone. Although it would be neat to watch the Sun's expansion to the red giant phase, as well as watching it collapse into a white dwarf. (From a safe distance of coarse.)

Littlemews
2003-Dec-22, 11:09 PM
Our sun is a G2 star, therefore it can't be turn into red giant, except White Dwarf...

Matthew
2003-Dec-23, 01:17 AM
Our sun is a G2 star, therefore it can't be turn into red giant, except White Dwarf...


No, our sun will got to the red giant stage, but not the red super giant stage. It will expand to encompass Mercury, Venus and probably Earth.

damienpaul
2003-Dec-23, 03:41 AM
okay, who reckons that the expanding sun will take Earth, who reckons it won't? Give a reason for your answer (spoken like a true chalkie)

lazserus
2004-Jan-01, 05:00 AM
According to every theory I've ever read the sun will expand beyond Earth, engulfing Mars as well. Conjecture states that every planet within the inner asteroid belt will be gobbled up by our little host star. How exciting!

However, if you do the calculations and compare them with the rate at which our big neighbor, Andromeda, is speeding towards us you'll find that the Milky Way will collide with the Andromeda galaxy in the next couple of billion years. That could prove more interesting than an expanding star. :D

damienpaul
2004-Jan-02, 12:35 PM
what do people think the combined effect of a galaxy collision and a supernova will be and can anyone make me and my better half immortal to witness it???

Sasha
2004-Jan-04, 12:31 AM
Okay.. you have said 5 billion years. Think of other things that could happen in that time. Meteors and other things that could wipe out part of the world. So when you think about it there's going to be a lot more worries facing the future human race other than the sun blowing out of little flames. And 5 BILLION YEARS. C'mon guys.. take the few past 100's of years our science evolved from nothing to something. Now take 5,000,000,000 and compare it to 500 yrs. Yeah. There's gona be huge discoveries and progress.. I am sensing it... *psychic* ooo.. :blink:

damienpaul
2004-Jan-04, 02:33 AM
this is very true, but i think it is interesting to discuss the death of our sun, i have a couple more questions related to it:

1. will it go nova?
2. will it form a planetary nebula?
3. from (2) will another system form?

Littlemews
2004-Jan-04, 08:40 PM
Originally posted by damienpaul@Jan 4 2004, 02:33 AM
this is very true, but i think it is interesting to discuss the death of our sun, i have a couple more questions related to it:

1. will it go nova?
2. will it form a planetary nebula?
3. from (2) will another system form?
For question No. 1, I answer Yes, because at that time Earth might become like Io, Jupiter's lagest Moon...super hot and lava rain every everyday

No.2 Yes again...since our Earth is a low mass star, therefore the chance for Earth to become a Plantary Nebula is high..

No. 3...not really know about it much, but it depends on our Sun's fate.

lazserus
2004-Jan-05, 01:40 AM
1. will it go nova?
It's always a possibility. Most stars go supernova just before reverting to a white dwarf. When a star expands into a red giant, the surface area obviously increases, which also means a higher quantity of surface material than it will have when it becomes a white dwarf. Where does all of it go? However, it won't be as energetic as a supernova.

For question No. 1, I answer Yes, because at that time Earth might become like Io, Jupiter's lagest Moon...super hot and lava rain every everyday
The problem with this thought is that there won't be an Earth left. Our star is supposed to grow 100 times its current size. This expands well beyond Earth's position in our solar system. Mars' position as well. Theory tells us that the expansion will actually make Europa livable.

2. will it form a planetary nebula?
The chances are rather high. We have a planetary system and when the star's surface explodes, there will be excess gas in the vecinity.

3. from (2) will another system form?
Doubtful. There just won't be enough gas. Most star formations happen within nebulae millions of light-years across with super dense gas.

Littlemews
2004-Jan-05, 01:56 AM
Theory tells us that the expansion will actually make Europa livable.
Even with Jupiter's radiation?

Matthew
2004-Jan-05, 03:41 AM
1. will it go nova?

Maybe, but not supernova, its not large enough for that.

damienpaul
2004-Jan-05, 11:21 AM
can i ask another silly question?

what is the difference between a nova and a supernova?

lazserus
2004-Jan-05, 07:02 PM
A nova is when a star's luminosity significantly increases and then it fades back to normal. Normally that happens within a span of a few months to a few years.

A supernova is when a star blows off it's outer layers in an explosive manner, expelling large quantities of high frequency radiation. Typically supernovae happen in stars with 5 solar masses or more.

From what I know, stars don't end in novae, just supernovae. Considering the star returns to its original luminosity after a nova and within a short period of time, it tends to happen during a life cycle as opposed to the end of one. When our sun expands to a red giant, it's goin to eventually collapse to a white dwarf - I guess you could say it will go nova, but it won't return to the red dwarf luminosity.

Littlemews
2004-Jan-05, 07:53 PM
Our sun will go supernova(White Dwarf)..hmm that's ture, but what happen next? White Dwarf Supernova (Nothing)? or Nutron Star or Black Hole (Massive White Dwarf)? I think the chance for our sun to become a neutron Star is high. ;)

Sun's Mass : 2*1020 kilograms
Luminosity : 111.16 (I think)

Hmm probably our sun wont turn into Neutron Star, or black hole, but leave Main Sequence and become a red giant...

damienpaul
2004-Jan-05, 11:28 PM
and generally be a nuisance for earth

lazserus
2004-Jan-05, 11:46 PM
Our sun will go supernova(White Dwarf)..
Yes, it will end in a white dwarf, but it surely won't go supernova. In order for a star to explode into a supernova it has to be a minimal of 5 solar masses. That means 5 times the mass of our sun.

Our sun is not massive enough to collapse into a black hole. We're considered a yellow medium. It would take a much more massive star than our own to collapse into a black hole. The fate of our sun is simple - brief red giant expansion, collapse to white dwarf. No black holes and no neutron stars. Our sun isn't massive enough to collapse that far. We're well within the Chandrasekhar limit.

damienpaul
2004-Jan-05, 11:52 PM
1. what is the ultimate fate of the sun

2. what is the Chandrasekhar limit?

lazserus
2004-Jan-06, 12:13 AM
1. what is the ultimate fate of the sun
white dwarf status

2. what is the Chandrasekhar limit?
The Chandrasekhar limit is the maximum mass of a white dwarf, and is approximately 3 1030 kg, around 1.44 times the mass of the Sun. This is the limit before it will collapse into a neutron star or black hole.

damienpaul
2004-Jan-06, 12:15 AM
a further silly question - when white dwarfs use up their fuel, what then?

lazserus
2004-Jan-06, 12:34 AM
Actually, that's not a silly question. There is no fuel to use up at this point. The only thing that keeps a white dwarf intact is electron degeneracy pressure (http://en2.wikipedia.org/wiki/Electron_degeneracy_pressure). If the mass is still above the Chandrasekhar limit then it will collapse further into a neutron star.

damienpaul
2004-Jan-06, 12:38 AM
neutron stars fascinate me, but i know so little, can someone please explain?

TheThorn
2004-Jan-06, 12:44 AM
White dwarfs have already used up their fuel. Before they use up their hydrogen they are main sequence stars, then as they "burn" heavier elements they are red giants. When that runs out, they become white dwarfs and then just slowly cool off, eventually becoming black dwarfs.

White Dwarfs (http://imagine.gsfc.nasa.gov/docs/science/know_l1/dwarfs.html)

No one here has mentioned the brief but spectacular "planetary nebula" phase that appears to come with the transition from red giant to white dwarf. That will probably be more fun to watch from a couple of light years away than it will be from here.

lazserus
2004-Jan-06, 12:44 AM
A neutron star is basically the next step below a white dwarf. Super dense, but very small in radius. A neutron star is typically the same density as the Sun, yet only has a radius of 10km, where a white dwarf's radius is roughly 25km. Neutron stars are held together by neutron degeneracy pressure as opposed to electron degeneracy.

damienpaul
2004-Jan-06, 12:46 AM
that is unbelievably small!!! can i assume the gravity would be the same? or will earth likely be a piece of burnt toast by then anyways?

lazserus
2004-Jan-06, 12:48 AM
The Sun probably would never collapse as far as a neutron star considering it's not massive enough. The Earth will definitely be sense long gone. The gravity stays the same.

Littlemews
2004-Jan-06, 12:49 AM
A neutron Star is the ball of neutrons created by the collapse of the iron core in a massive star supernova, high massive than the sun. Neutron stars are essentially giant atomic nuclei, with 2 important differences :
1. They made almost entirely of neutrons.
2. Gravity, not the strong froce, is what binds them together.


---------------------
If the earth were visited by a N.star, it would be squashed into a shell no thicker than your thumb on the surface of the N.star.

damienpaul
2004-Jan-06, 12:50 AM
so to a black dwarf it'll go? what is a black dwarf and have they ever been detected?

lazserus
2004-Jan-06, 01:07 AM
I've never heard of a black dwarf, but I've heard of a brown dwarf.

damienpaul
2004-Jan-06, 01:12 AM
ok, but would the sun fizzle into a brown dwarf... leading to another question...what of jupiter?

Littlemews
2004-Jan-06, 01:20 AM
Originally posted by damienpaul@Jan 6 2004, 01:12 AM
ok, but would the sun fizzle into a brown dwarf... leading to another question...what of jupiter?
No, Our sun wont fizzle into BD, because our sun is not a fail star while forming...

damienpaul
2004-Jan-06, 01:21 AM
please explain...i am intrigued

Littlemews
2004-Jan-06, 01:23 AM
Originally posted by lazserus@Jan 6 2004, 01:07 AM
I've never heard of a black dwarf, but I've heard of a brown dwarf.
When a WD cool down (Dark), eventually they turn into Black Dwarf..

Littlemews
2004-Jan-06, 01:26 AM
BD : an object too samll to become a ordinary star because of the D.Pressure, so it collapse before fusion becomes self-sustaining. Other word, a Fail Star

damienpaul
2004-Jan-06, 01:26 AM
are there any postings with info on that phenomena?

lazserus
2004-Jan-06, 02:09 AM
I did a little research and finally found it. Brown dwarfs are failed stars, but Jupiter is not considered one. A brown dwarf is a star that never fused into helium cores. However, the masses are 13-70 times the size of Jupiter. Jupiter is just a planetary gas giant, not a failed star. Black dwarfs are exactly what was mentioned before - a white dwarf that eventually cools.

damienpaul
2004-Jan-06, 03:53 AM
cool, thank you for that, are there any other black dwarfs known and would they possess the ssame gravity as a white dwarf?

Littlemews
2004-Jan-06, 04:22 AM
The mass still exist when it cools down, but lower, same as the luminosity...soon it will collapse and then disppear in the universe ><.

damienpaul
2004-Jan-06, 04:23 AM
so a very heavy dark mass :blink:?

Littlemews
2004-Jan-06, 04:49 AM
Originally posted by damienpaul@Jan 6 2004, 04:23 AM
so a very heavy dark mass :blink:?
>< Don&#39;t know how to explain... but with this image I am sure u will understand :lol:

http://lithops.as.arizona.edu/~jill/EPO/St.../StarPower4.pdf (http://lithops.as.arizona.edu/~jill/EPO/Stars/StarPower4.pdf)

damienpaul
2004-Jan-06, 04:50 AM
so we can assume that mercury, venus, earth and possibly mars will be cactus when the sun chucks its celestial wobbly, but what do folks think will happen to the other planets?

damienpaul
2004-Jan-06, 04:52 AM
image is good, bobo like&#33;&#33;&#33; :lol:

Littlemews
2004-Jan-06, 04:53 AM
Dunno ;)

damienpaul
2004-Jan-06, 04:55 AM
is it conceivable that much of the gas, particularly off jupiter will be blown off?

Littlemews
2004-Jan-06, 06:40 PM
Maybe, but not so sure about it, because most of the scientist think, Jupiter is huge and it can produce heat into space...2x of the heat.

My stupid calculation :
The sun when turn into White Dwarf...10,000 brightness of the normal sun, I don&#39;t count the temperature of the Sun&#39;s Core, but the surface. 6000 x 10,000 = 60,000,000 K....Jupiter&#39;s Distance from Sun its 5.2 AU = 78,000,000 Km
and Earth&#39;s distance from Sun is 1 AU = 15,000,000 km.

780mil - 600mil = 180mil

180mil (After WD), and 150mil (Earth&#39;s Distance form Sun), so compare to those 2 planet...Jupiter is in between Earth and Mars...which is about 1.2 AU from the White Dwarf....so Jupiter is safe..I guess

damienpaul
2004-Jan-06, 11:12 PM
ummm can you clarify your equations???

kashi
2004-Jan-07, 12:39 AM
I don&#39;t think a 10000 fold increase in brightness corresponds to a 10000 fold increase in temperature at all. Nor does the 600000000 K have anything to do with distance.

damienpaul
2004-Jan-07, 12:51 AM
i am getting further confused&#33;&#33;&#33;&#33; what will the solar system be like when the sun is a white dwarf

TheThorn
2004-Jan-07, 01:09 AM
Cold.

damienpaul
2004-Jan-07, 01:22 AM
specifically....

Tinaa
2004-Jan-07, 01:48 AM
On the Hertzprung-Russell (HR) diagram white dwarfs are found on the low left part making them dim, hot stars. Their luminosity are from 1 to 10^-4 and their spectrral classes run from F to B. I agree with TheThorn, it will be cold and dark. Poor Titan, if it does manage to evolve life during the Red Giant stage, they will freeze to death.

damienpaul
2004-Jan-07, 02:04 AM
darn&#33;&#33;&#33;&#33; so will mars exist?

Tinaa
2004-Jan-07, 02:14 AM
So, what do you have against Mars?

damienpaul
2004-Jan-07, 02:21 AM
no no no, i am hoping that mars does exist.....my avatar ought to give a hint

Littlemews
2004-Jan-07, 02:36 AM
Who know what might happen to Mars at that time :lol: , but one thing for sure, Mars will cover by the WD and u almost can&#39;t see it until it complete dark...can&#39;t see it anymore

damienpaul
2004-Jan-07, 02:51 AM
a total martian-solar eclipse....hmmmmmmmm&#33; what a sight that&#39;d be

Tinaa
2004-Jan-11, 05:12 AM
Here (http://antwrp.gsfc.nasa.gov/apod/astropix.html) is a great example of what our sun&#39;s future will be, January 11th APOD.

Littlemews
2004-Jan-11, 05:19 AM
Nice image :lol: This is a white dwarf as well, I think someone already post it before :) White Dwarf Supernova

http://www.antville.org/img/2012/novaish.jpg

kashi
2004-Jan-11, 01:32 PM
Our sun will not go supernova, assuming scientists&#39; calculations are correct.

GOURDHEAD
2004-Jan-11, 02:44 PM
If the Big Bang is taken as the true beginning of the current configuration of the universe, has there been time for a sun-like star to evolve to a black dwarf?

Will each surviving planet continue to increase in mass such that Jupiter will attain stellar mass by the time the sun becomes black? Since the sun will continue to exceed Jupiter in mass, because its gravity well is larger and it will collect more mass from the interstellar medium than Jupiter, will it remain near the center of gravity of the system and invisibile though not a black hole in the usual sense?

GOURDHEAD
2004-Jan-11, 03:08 PM
Oops&#33; Sorry about the double submittal

TheThorn
2004-Jan-11, 03:32 PM
If the Big Bang is taken as the true beginning of the current configuration of the universe, has there been time for a sun-like star to evolve to a black dwarf?

That&#39;s a very good question. I think the answer is no. It takes a long time for a white dwarf to form in the first place, and then another long time for it to cool off. Another part of the problem is at what point is this cooling star "black"?

From http://physics.weber.edu/palen/Phsx1030/Le...ures/Lwdns.html (http://physics.weber.edu/palen/Phsx1030/Lectures/Lwdns.html)

A 0.6 MSun star will:

* drop to a luminosity of 0.1 LSun in 20 million yrs.
* drop to a luminosity of 0.01 LSun in 300 million yrs.
* drop to a luminosity of 0.001 LSun in 1 billion yrs.
* drop to a luminosity of 0.0001 LSun in 6 billion yrs.

i.e. a white dwarf with .6 of the mass of the sun will take 6 billion years to cool to the point that it has .0001 times the light output of the sun. But at that point it&#39;s surface temperature has only drpped back to the same as the sun&#39;s (it&#39;s just so small that it isn&#39;t very bright). I&#39;d hardly call something as hot as the sun "black". More "yellow". And since the cooling process slows as the temperature decreases, it&#39;s going to take even longer to get to "black" whatever temperature you choose for that.

Yet to even get to the white dwarf stage, a star that small would take a long time. If we assume that it started life the size of the sun, and lost 40% of it&#39;s mass in the red giant / planetary nebula phase, it would have taken it about 10 billion years before it became a white dwarf of .6 Msun. Another 6 billion years to get back to yellow, and we&#39;re already past the best current estimates of the age of the universe according to the big bang theory.

Bigger stars get to the white dwarf stage faster, but cool more slowly, because they are physically smaller (sounds wrong, but that&#39;s the way it is).

As for your second question, I doubt that any of the planets are accreting matter anywhere near the rate needed to become stars. And that planetary nebula phase could be quite disruptive. The inner planets won&#39;t survive the red giant phase. If Jupiter survives the planetary nebula phase (IMHO, it is likely that at least its core will survive) then it will eventually cool to the background temperature of the universe (currently 3 degrees K).

Which brings me back to my previous post.

Cold.

;)

Littlemews
2004-Jan-11, 07:44 PM
Bigger stars get to the white dwarf stage faster, but cool more slowly,
Writting Notes........another question, so small stars get to the white dwarf stage slower, but cool more faster? As I know, bigger star has more luminosity, and they cool down really quick after the explosion, so small stars has lower luminosity, and they cool down really slow...Does Size of the stars has something to do with the luminosity? :)

TheThorn
2004-Jan-12, 04:44 AM
Originally posted by Littlemews@Jan 11 2004, 07:44 PM

another question, so small stars get to the white dwarf stage slower, but cool more faster? As I know, bigger star has more luminosity, and they cool down really quick after the explosion, so small stars has lower luminosity, and they cool down really slow...Does Size of the stars has something to do with the luminosity? :)
Luminosity is a function of temperature and physical size. Massive main sequence stars are both bigger and hotter than less massive stars, so they are very bright. They burn their fuel quicker so their lives are shorter, and they get to the white dwarf stage sooner (assuming they&#39;re not too big).

But in the white dwarf stage that changes. I&#39;m not sure whether the initial temperature of a white dwarf depends on mass, but its size certainly does, but backwards. More massive white dwarfs are smaller.

From that link I posted earlier:

They are made mainly of electron-degenerate matter, which means that the pressure does not respond to an increase in temperature in the usual way. This causes white dwarfs to have the odd property that if their mass increases their radius decreases.

* a 0.5 MSun white dwarf has a radius of 1.5 REarth
* a 1.0 MSun white dwarf has a radius of 0.9 REarth
* a 1.3MSun white dwarf has a radius of 0.4 REarth

Since the surface area of a sphere varies with the square of the radius, the 0.5Msun white dwarf would have a surface area 14 times bigger than the 1.3Msun white dwarf, making it 14 times more luminous at the same temperature, radiating 14 times as much energy. And since it only has 38 percent of the mass, it would be cooling about 14/.38 = 37 times as fast.

Like I said, the massive stars get to that stage quicker, but cool more slowly.

Tiny
2004-Jan-12, 04:54 AM
Does our sun a massive star in the Main Sequence (G2)?

Littlemews
2004-Jan-12, 05:20 AM
so basically Size didn&#39;t affect the temperature or luminosity at all, except its mass...high mass die faster, and low mass live longer

Bluewolf027
2004-Jan-12, 05:40 PM
Originally posted by Littlemews@Nov 26 2003, 04:43 AM
5 billion yrs later, yea 5 billion yrs later, the sun use up its energy and become White Drawft...hmm then is this the end of human race? We cant live on Jupiter or other Jovian planets right? So any good idea about where we, human can live?
To answer the original question the earth will be gone long before the sun becomes a white dwarf. If we are around still we will have been living somewhere else in the universe for a couple of billion years already.

http://curious.astro.cornell.edu/question.....php?number=232 (http://curious.astro.cornell.edu/question.php?number=232)

Tiny
2004-Jan-12, 06:49 PM
I did a little research about this topic :
- Because our sun is a Hot gas burning star (Hydrogen to helium) Temperature from 6000K(surface) to 15million K(inside), High Temperature = High Mass, therefore it won&#39;t got planetary nebula eventually.

- Most of the star die in planetary nebula, because their lifetime as a star which can&#39;t live too long, like 50,000 years maximun, but our sun, I mean the limit lifetime for our sun is 9 - 10 billion years, so the sun either go with White Dwarf or a neutron star (I think), or black hole (If it has enough mass) after the Sun use up its fuel buring...

Where can we live after the Sun is gone?
- other side of the our galaxy maybe, or space travel...

Tinaa
2004-Jan-12, 10:55 PM
Here (http://www.anzwers.org/free/universe/hr.html) is an example of a HR diagram. The sun is found almost right in the middle of the yellow stars is the Main Sequence. You can also look towards the bottom left of the diagram and see the white dwarfs, upper right are the red giants. Our star, for example, is a G2. It will eventually become a red giant and then a white dwarf. Most stars occupy different sections of the diagram during their lives.

Tiny
2004-Jan-12, 11:15 PM
Thanks for that HR Diagram, I think I start to understand now...

Hot, Blue color, higher Luminosity and higher massive has shorter life
Like B2 stars in the MS ^^ <<<<this types of star can live like 5 mil - 30 mil years

Cool, Red color, dim, and lower massive live longer
Like MO Stars in the MS <<<<this type of star can live like 10 bil - 60 billion years

Am I am right? :unsure:

Matthew
2004-Jan-13, 02:16 AM
Hot, Blue color, higher Luminosity and higher massive has shorter life
Like B2 stars in the MS ^^ <<<<this types of star can live like 5 mil - 30 mil years

Cool, Red color, dim, and lower massive live longer
Like MO Stars in the MS <<<<this type of star can live like 10 bil - 60 billion years

Am I am right?

The color of a star relates to its surface temperature. Cool stars are red, hot stars are blue. Luminosity relates to the star&#39;s size and temperature. Main sequence stars live for billions of years.

Supermassive stars live for only a few million years because of their emmense preassure which convertshydrogen into helium much faster.

VanderL
2004-Jan-16, 05:14 PM
And what about the variable stars, the ones that go through the Hertzsprung-Russel diagram as if it were a racetrack? Any ideas on how it is possible that FG Sagittae changed from a hot giant (in 1900, 50000K) to a "late spectral type" cool star (4000K) in the 1990&#39;s?
That would mean it raced through the "main sequence" in under a century, how is that for stellar evolution&#33;
Cheers.

Tinaa
2004-Jan-17, 04:53 AM
FG Sagittea is a carbon star struggling to keep its "home fires burning," by fusing helium into carbon. Eventually the the star&#39;s core will become iron and the fusion stops. Supernova&#33; The star blows off those heavy elements. It is a wonderful ending, for this ending allows for the formation of planets like our own.

damienpaul
2004-Jan-17, 11:14 AM
okay, i have a seemingly silly question, what is the order of fusion in a star - i know that hydrogen goes to helium...but then i get a bit lost... And that is pretty darned fast VanderL&#33;

VanderL
2004-Jan-17, 01:10 PM
Wait a minute Tinaa,
FG Sagittae is in a supernova remnant itself, does that mean a star can go supernova twice?
I still don&#39;t understand how a powersource of a giant star can turn it&#39;s fusion engine down and cooling from 50,000 K to 4,000 K in a few decades. Current wisdom is that in our Sun it takes 100,000 years for heat to get from the core to the surface. Or are the implications that in variable stars the heat source is only at the surface, in which case the electric model makes more sense, since it poses that all the energyconversion happens exactly at the surface.
Damienpaul, it isn&#39;t strange that you have trouble remembering all the different steps in the fusion model, there&#39;s so many steps, I&#39;ll try to find the correct sequence that is thought to act in our Sun&#39;s core.

VanderL
2004-Jan-17, 03:25 PM
Damienpaul, my view is of course that nuclear fusion is not the powersource of a star so the next bit is a "colored" version of the fusion process (taken from Wal Thornhill&#39;s website).
http://www.holoscience.com/news/puzzle.html
Here the proton-proton reaction is described and also how improbable this fusion recation is.
The neutrino&#39;s generated in this way are too low-energy to detect, so there is a side chain of fusion that produces detectable neutrino&#39;s (involving 3 He and 4 He particles to form a beryllium nucleus (7 Be) which then captures a proton to form a boron nucleus (8 B); this nucleus then breaks up into Beryllium (8 Be) plus a positron and neutrino).
He argues that the neutrino detection that shows only a third of the expected number, is correct (so no neutrino-oscillation fudging is necessary) and means that fusion is not an important process in the Sun. Furthermore, the fact that neutrino numbers vary with the solar (sunspot) cycle indicates that the fusion is not to be found in the Sun&#39;s core, but at it&#39;s surface.
Hope this helps, some googling will show the rest of the fusion reactions for the heavier elements.
Maybe I can add that the easiest way to produce heavier elements is through an electrical plasma pinch device.
Cheers.

damienpaul
2004-Jan-17, 03:34 PM
Thank you VanderL - it is actually clear to me now, well the first part as described. Ok I bite, what is the electrical plasma pinch device?

VanderL
2004-Jan-17, 04:04 PM
http://public.lanl.gov/alp/plasma/universe.html

Here is the site of Anthony Peratt explaining how plasma works, there is a section called Laboratory Astrophysics where all kinds of devices are mentioned, basically the Z-pinch machine is what plasma physicists use to get a nuclear fusion reaction going. They do it efficiently by using electricity, and why would Nature do it any different (if nothing else, Nature is efficient). As I understand it, all the 60 elements found in the Sun&#39;s spectrum can be generated in this way.
Cheers.

damienpaul
2004-Jan-17, 04:40 PM
which 60 elements...i know of hydrogen and helium, but what of the remaining 58??? :blink:

VanderL
2004-Jan-17, 05:17 PM
http://csep10.phys.utk.edu/astr162/lect/su...omposition.html (http://csep10.phys.utk.edu/astr162/lect/sun/composition.html)

Here is the list.
Cheers.

Tinaa
2004-Jan-17, 05:44 PM
Helium Flashes. The heat flash causes the star&#39;s envelope to grow huge in 3 to 50 years. There are also different kinds of supernovae and then there are novae. Here (http://antwrp.gsfc.nasa.gov/apod/ap970925.html) is an example of a repeating nova.

Also check this (http://zebu.uoregon.edu/~js/ast122/lectures/lec11.html) out.

VanderL
2004-Jan-17, 06:54 PM
Thanks Tinaa,

I know there are a whole bunch of fusion processes, convection and expansion/contraction phenomena described to explain the zoo of star types and star properties. To me it seems that every star type has it&#39;s own specific set of characteristics that CAN be explained by the complex processes that are assumed. The problem to me is the lack of a logical mechanism that makes stars behave the way they do. There is never one process responsible for all the star properties that we can see (sometimes there is no fuel, sometimes there is too much fuel, sometimes gravity is responsible, sometimes magnetism etc). This seems like "epicycling" to me, everything is very complex and imo unnecessarily so. An example; recently a star was described (Arechnar) that is 50% flatter at the poles than at the equator. Theory did not expect this, so now a bunch of scientists are trying to explain this observation by modifying the theory and this will probably lead to a triumphant article very soon.
I think this has been going on for quite some time (every new observation is a new class of stars, like V838 Mons seems to be) and it means that we don&#39;t really know what makes a star shine and we should be prepared to accept that our current model is wrong and look for viable alternatives.
Cheers.

Tinaa
2004-Jan-19, 02:04 AM
Here (http://tim-thompson.com/hr.html) is a site that explains why the elcetric universe version of star formation is junk.

Check this one (http://www.tim-thompson.com/electric-sun.html) out too. It really takes apart the electric sun theory&#33;

damienpaul
2004-Jan-19, 02:38 AM
So helium flashes could conceivably occur with our sun when it reaches a white dwarf?

Wow, that is some debunking of the electric universe theory.