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I What is the average number of planets per star?

  1. Sep 21, 2016 #1
    What is the occurrence rate of planets? I'm not talking about earth-like planets, but any planet in general. I can't find a source that examines this number, all I can find is the average number of earth-like planets. Can anyone lead me to a useful paper/source? Thanks in advance
  2. jcsd
  3. Sep 21, 2016 #2
    Our present technologies for detecting exoplanets are not yet advanced enough for a reliable estimate of an average number.
    Many smaller planets could exist that we don't yet know about, but more capable technologies are probably not far away in the future.
    What has been established so far is that stars having at least one planet is commonplace, and stars with several planets are not unusual.
    In particular the ocurrence of very large planets close to the parent star ('hot Jupiters') has been higher than expected.
  4. Sep 21, 2016 #3


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    Do we even have a definition for planet that extends to other stars?
  5. Sep 21, 2016 #4
    According to a study done in 2012 and published in Nature, there may be as many as one planet, or more, per star in the Milky Way galaxy.
    http://www.nature.com/nature/journal/v481/n7380/full/nature10684.html - Nature 481, 167-169, January 12, 2012 (arXiv free reprint)

    Last edited by a moderator: May 8, 2017
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