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Stellar size limit

  1. Apr 17, 2005 #1
    Astronomers announced that stars have a size limit. What does it say about stars' cores? This is still unknown i'd say.

    Btw a new yellow star was discovered outside the solar system. Looks very much like our sun.
     
    Last edited: Apr 17, 2005
  2. jcsd
  3. Apr 17, 2005 #2

    SpaceTiger

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    Note that this likely only applies to stars formed recently. Early stars may not be constrained by such limits, as extremely low-metallicity gas will behave quite differently in the process of collapse.


    Nothing that I can think of. It mostly just has implications for the process of star formation; that is, the collapse and fragmentation of the molecular clouds.


    I don't think the star was recently discovered, as it's very nearby. This is a story about the first direct imaging of a planet outside the solar system. It was possible because the planet is so far away from its host star.
     
  4. Apr 17, 2005 #3
    Thanks for reply SpaceTiger. It seems there is some unknown force which triggers star formation. Cold gas clouds collapse to form stars. Looks like powerful magnetic fields.

    I think the star is named SO025300.5+165258 but i'm not sure though. In 2000 eight new stars were discovered, among them are Sedna and Quaoar. There appears to be an Earth-like planet some 50 light years away. It could be part of another solar system.

    Regards
     
    Last edited: Apr 17, 2005
  5. Apr 17, 2005 #4

    SpaceTiger

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    The trigger of star formation probably isn't the issue. It has more to do with the details of the cloud's collapse.


    Those are both Kuiper Belt objects, not stars.
     
  6. Apr 17, 2005 #5

    Chronos

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    Theory and observational evidence suggests metallicity drives down the average and maximum mass during star formation:

    On the variation of the Initial Mass Function
    http://arxiv.org/abs/astro-ph/0009005

    Evidence for a fundamental stellar upper mass limit from clustered star formation
    http://arxiv.org/abs/astro-ph/0310860

    Very early [population III] stars, which formed when there was little or no metallicity, could have been truly massive compared to the largest stars we see today:

    The First Stars
    http://arxiv.org/abs/astro-ph/0311019

    Three Epochs of Star Formation in the High Redshift Universe
    http://arxiv.org/abs/astro-ph/0208447

    Unfortunately, there are none of these big fellows near enough for us to get any decent mass measurements. Then again, that really isn't so unfortunate after all. They are thought to be the progenitors of gamma ray bursts. You really would not want any of these things living in your galactic neighborhood.

    Star formation is typically triggered by disturbances in the interstellar medium. Galactic merges trigger huge bursts of star formation activity. Shock waves from supernovae are also frequently blamed, as in the case of our very own near and dear sun.
     
  7. Apr 17, 2005 #6
    AFAIK starbirth is triggered by GMCs.
     
  8. Apr 17, 2005 #7

    SpaceTiger

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    Stars are born inside of GMCs, but the cause of the cloud's collapse is the issue being addressed.
     
    Last edited: Apr 18, 2005
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