Earth sized lava world discovered

  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.

    Last edited by a moderator: Aug 22, 2013
  2. jcsd
  3. Greg Bernhardt

    Staff: Admin

    Do you have a link for the news story?
  4. Drakkith

    Staff: Mentor

    Okay. Did you have some kind of question about it?
  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.
  6. mfb

    Staff: Mentor

    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.
  7. They're orbiting a non-main sequence star.
  8. mfb

    Staff: Mentor

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

    Staff: Mentor

    Any idea what the density of a red giant's atmosphere is at that distance?
  10. mfb

    Staff: Mentor

    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...
  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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