Smallest extrasolar planet found to date

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Lucas, Jun 13, 2005.

  1. Lucas Registered Senior Member

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    http://www.cnn.com/2005/TECH/space/06/13/extrasolar.planet/index.htm

    "Astronomers announced Monday the discovery of the smallest planet so far found outside of our solar system.

    About seven-and-a-half times as massive as Earth, and about twice as wide, this new extrasolar planet may be the first rocky world ever found orbiting a star similar to our own."


    I bet that there are extrasolar planets smaller than this one, this orbits around the star Gliese 876, in the Cosntellation Aquarius


    Edit: the CNN link doesn't work. Check this instead
    http://www.newscientistspace.com/article.ns?id=dn7517
     
    Last edited: Jun 16, 2005
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  3. Lucas Registered Senior Member

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    Last edited: Jun 13, 2005
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  5. eburacum45 Valued Senior Member

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    The best model I have seen of Gliese 876 d gives it a gravity of about two gee, a diameter twice that of Earth, a temperature above 400k, and a minimum molecular weight retention between 2 and 3 (not sure what that means exactly);
    but it should hold onto Helium if not Hydrogen, and any heavier gases as well.
    So it would have a dense atmosphere, but there is a lot of uncertainty as to how thick.

    If the pressure at the bottom of the atmosphere is twenty or thirty times as great as on Earth a water ocean is possible at 200 celsius; however the greenhouse effect would probably make the surface temperature even higher than that.

    Here is my image of it using Celestia
    http://img66.echo.cx/img66/9905/d0fb.jpg
     
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  7. eburacum45 Valued Senior Member

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    The three or four small planets around the pulsar PSR 1257+12 probably formed from the debris of the supernova that also formed the pulsar; they are far from being Earthlike, as they are in a very inhospitable system.
    Pulsar planets are generally considered separately from other extrasolar worlds.

    Check out
    http://www.extrasolar.net/
    for more info.
     
  8. Lucas Registered Senior Member

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    So maybe those "pulsar planets" shouldn't be called planets at all, if they were formed through a different process, don't you think? I've seen some people calling them "asteroids", due to their smallness. The term planet should only be reserved to bodies formed due to the aggregation of planetesimals in the solar nebula phase.

    More news: this new earthlike planet around the red dwarf can't be studied with the technique known as "transit photometry", due to the particular inclination of the system:
    http://www.universetoday.com/am/publish/how_earthlike_rocky_planet.html?1562005
     
    Last edited: Jun 16, 2005
  9. Lucas Registered Senior Member

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  10. Sagebrush Registered Member

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    Could these planets be survivors of the supernova?
    If our own sun went supernova, wouldn't the core of Jupiter survive?
     
  11. Communist Hamster Cricetulus griseus leninus Valued Senior Member

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    Our sun can't go supernova, it isn't big enough.
     
  12. Sagebrush Registered Member

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  13. Lucas Registered Senior Member

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  14. Sagebrush Registered Member

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    Thanks, that link is very informative!
     
  15. Okeydoke Registered Senior Member

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