The end of the Sun

Discussion in 'Astronomy, Exobiology, & Cosmology' started by mstarry, Feb 10, 2006.

  1. Xylene Valued Senior Member

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    1,398
    Yes, it's about that time from apes to Humans, in terms of the time we seperated from the same line of descent as them.
     
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  3. Lucas Registered Senior Member

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    Incidentally, I adhere to the idea of star lifting (Criswell, 1985), i.e., removing mass of the Sun, so it won't become a red giant. Hence, it would exist as a white dwarf during a prolongued period of time. But I don't know if life on Earth could exist under the feeble rays of a white dwarf
     
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  5. eburacum45 Valued Senior Member

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    If you practice Star Lifting you could illuminate the Earth for billions of years by fusing the hydrogen you have extracted. Just put a ring of artificial sunlets round the Earth ()and any other planet you want to live on) and fuse the hydrogen gradually.
    A large proportion of the hydrogen in a Sun-like star never gets fused anyway; this is much more efficient.
    http://en.wikipedia.org/wiki/Star_lifting
     
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  7. Odin2006 Democratic Socialist Registered Senior Member

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    When the Sun runs out of hydrogen in it's core, the core with contract and heat up, thos will cause the hydrogen just outside the core to start fusion. This hydrogen shell fusion gives off more energy than core fusion, causing the outer layers to puff out and cool, the density of the gas in red giants outer layers is extremely thin, thin enough it would be considered a near vacuum on earth. The sun's core continues to contract untill it becomes hot enough for the fusion of helium into carbon and oxygen to start, this causes the core to expand again, slowing the hydrogen fusion surrounding the core, causing the outer layers of the star to become more dense and hot again. When the Helium buring stops the core contracts and the outer layers puff out again. The sun is not massive enough to fuse heavier elements, and it enters the Asymptomic Red Giant phase, and becomes a Mira-type variable. There is no core fusion but there is still an inner shell of fusing helium and an outer shell of fusing hydrogen. The fusion in the helium-buring shell is extremely sensitive to changes in temperature and presure, causing the pulsations typical of stars like Mira. The pulsations eventually become powerful enough to lift the outer layers from the core, creating a planetary nebula, and the core becomes a white dwarf the size of the earth, which slowly cools from then on.
     
  8. Avatar smoking revolver Valued Senior Member

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    Chances are the Sun will never run out of hydrogen, if our Solar system is unlucky enough in the collision between the Milky Way and Andromeda galaxies, current measurements suggest that in about five billion years the Milky Way and Andromeda will most likely collide.
     
  9. Novacane Registered Senior Member

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    Any good calendar dates on when that event is going to happen?
     
  10. invert_nexus Ze do caixao Valued Senior Member

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    God damn, your lame.
    Don't you ever get tired of... "Don't forget to check your watch" or "Don't forget to mark your calendar" or any one of a hundred other hackneyed and boring smartass phrases you've posted in your many guises?
    At least you're predictable. Never have to guess who Norman is this week...

    By the way, since you're so dependent upon the forums for your entertainment and all, have you donated to the cause yet?
     
  11. Poincare's Stepchild Inside a Klein bottle. Registered Senior Member

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    The Sun has a finite amount of hydrogen. It has to run out sometime. The figure I have seen most often is about 5 billion years.
     
  12. Novacane Registered Senior Member

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    After another 5 billion years after the sun reaches the Red Giant stage, the sun's starts a 5 billion year march to become a White Dwarf star. Question. How long does it remain a White Dwarf? Any guesses?

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  13. Odin2006 Democratic Socialist Registered Senior Member

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    There is enough space between stars that galactic mergers will only affect thier orbits, there will be no collisions between individual stars.
     
  14. Poincare's Stepchild Inside a Klein bottle. Registered Senior Member

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    I am not absolutely sure, but I think you are off on your time scales. I think the red giant stage is pretty short, in terms of a star's life. The collapse to a white dwarf comes fairly quickly, as soon as the helium fuel runs out.

    As the star collapses, it heats up a great deal. This is why it is white. It will last a long time as a white dwarf. It has only a relatively small surface area to radiate the residual heat. How long? 100's of billions of years, maybe a trillion.

    Unless it comes close to another star and sucks off enough mass. If it reaches 1.4 solar masses...BOOM...Type 1A supernova.
     
  15. Poincare's Stepchild Inside a Klein bottle. Registered Senior Member

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    True. Even with 100's of billions of stars involved, the odds of direct collisions between stars is pretty small.

    I have seen one computer prediction made by NASA that the Milky Way and Andromeda will collide in about 3 billion years, followed by a second collision 1 or 2 billion years after that. Both galaxies will have a lot of stars thrown out of them by these collisions. Following the second collision, the two galaxies will merge into one.
     
  16. Avatar smoking revolver Valued Senior Member

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    Not if it explodes before that, however I agree that the chances in our region are pretty small.
    Uhu, but there's still a chance and there most likely will be collisions in the more packed regions (which we aren't a part ot).
    Besides we don't need some other star to crash into our Sun,
    if we'll be on the galactic side which will have the first contact and happen to be unlucky enough, gamma ray bursts will probably boil our atmosphere away.


    However I still think and suspect that it won't be another star or a gamma ray burst, but our Sun in the red giant stage when the Earth ceases to be habitable by any life form.

    So we'd either have to get further away from it or die.
    =========

    http://www.space.com/scienceastronomy/astronomy/galaxy_collides_020507-1.html

    So it seems my 5 billion date was outdated. It's either 3 or 10
     
    Last edited: Apr 4, 2006
  17. Avatar smoking revolver Valued Senior Member

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    What is more interesting is that the super massive black holes at the centre of the galaxies are going to merge. Any after-effects from that?
     
  18. leopold Valued Senior Member

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    if i am correct the sun isn't big enough to go nova
    but it can turn into a red giant
     
  19. Avatar smoking revolver Valued Senior Member

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    according to all we know - it surely will
     
  20. leopold Valued Senior Member

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    Supernovas can occur in that small percentage of stars having a mass greater than 8 to 10 times the mass of the sun and perhaps in certain binary stars.
    http://www.answers.com/topic/supernova

    the following is the only thing i can find regarding nova
    A nova (pl. novae) is a cataclysmic nuclear explosion caused by the accretion of hydrogen onto the surface of a white dwarf star.
    http://www.answers.com/main/ntquery?method=4&dsid=2222&dekey=Nova&curtab=2222_1&linktext=Nova
     
  21. Avatar smoking revolver Valued Senior Member

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    19,083
    I was talking about the red giant, not the sun going nova
    sorry if I was not clear enough about it
     

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