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Earth sized lava world discovered

  1. Aug 21, 2013 #1
    I've recently read that an Earth sized planet that is a lava world orbit its star closer than Mercury orbits the Sun that was recently discovered.

    http://local.msn.com/new-planet-discovered-with-a-lava-ocean-and-an-8-hour-year

     
    Last edited by a moderator: Aug 22, 2013
  2. jcsd
  3. Aug 21, 2013 #2

    Greg Bernhardt

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    Do you have a link for the news story?
     
  4. Aug 21, 2013 #3
  5. Aug 22, 2013 #4

    Drakkith

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    Okay. Did you have some kind of question about it?
     
  6. Aug 22, 2013 #5
    No. Not really. I just find it to be an interesting find. Apparently, if I'm not mistaken from reading that article, it is closer to its star than it was thought that a planet can be. I may have misread though and that's not actually the case.
     
  7. Aug 22, 2013 #6

    mfb

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    Hotter, closer, shorter year (and probably denser as well)
    It is unclear how those planets formed and how their orbits developed, but that's just our lack of knowledge about planet formation in general. Up to 20 years ago, there was just one known example of a planetary system.
     
  8. Aug 22, 2013 #7
    They're orbiting a non-main sequence star.
     
  9. Aug 22, 2013 #8

    mfb

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    I think that just makes the planets around Kepler-70 even more surprising. For a while, the planets orbited in the star!
     
  10. Aug 22, 2013 #9

    Drakkith

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    Any idea what the density of a red giant's atmosphere is at that distance?
     
  11. Aug 22, 2013 #10

    mfb

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    Hmm... with values from Wikipedia:
    The current average density of the sun is 1400kg/m^3, but most of the volume has a density of less than 20g/m^3, with less than .2g/m^3 in the outer 30% of its diameter). In the late stages of hydrogen burning, it will increase its radius by a factor of 200. In addition, it loses some mass. If the relative densities stay the same (they probably won't), this would reduce the density by a factor of ~10 million, leaving 200ng/m^3 to 2 µg/m^3. That is a good vacuum.

    With the latter value and an orbital velocity of 100km/s (arbitrary value), not including gravitational interactions with the gas, a planet of the size of earth would collect mass at a rate of 2.5*10^8 to 2.5*10^10kg/s. This gives a stopping timescale of 7.5 to 750 million years. Not so wrong...
     
  12. Aug 22, 2013 #11
    Nice find Jupiter60, now with less speculation we can calculate what will happen to planets Mercury and Venus a billion years from now.
     
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