XPost: sci.astro.research   
   From: '''newspam'''@nezumi.demon.co.uk   
      
   On 08/06/2017 20:26, Phillip Helbig (undress to reply) wrote:   
   >> In as much as galaxy and star planetary system size distributions   
   >> are different, are two different formation temperatures required   
   >> within the concept of Jeans' length?   
   >   
   > The Jeans length is important for star formation, but the stuff which   
   > forms (rocky) planets is only a small fraction of a larger cloud which   
   > collapsed (as described by Jeans) to form a star.  There doesn't seem to   
   > be a lower limit on the size of "planets".  There is an obvious upper   
   > limit for (gaseous) planets---stars.  The sizes of planets are   
   > determined more by accretion, where gravitation is only one factor.   
      
   That suggests an interesting question.   
      
   Is it possible to compute either by simulation or from observations what   
   percentage of ordinary matter is tightly bound together (either   
   gravitationally or electromagnetically) as a function of length scale   
   (or mass).   
      
   There is clearly everything from ionised hydrogen, neutral hydrogen   
   (which must be a fair chunk in itself) dust grains and upto ~300Msun.   
   Does it obey some power law or are the preferred mass/length scales?   
      
   --   
   Regards,   
   Martin Brown   
      
   --- SoupGate-Win32 v1.05   
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