Planet Foramtion without stars

In summary, the conversation discusses the possibility of planet formation without a star in a dark system. It is noted that a central body, such as a brown dwarf, can be massive enough to support planet formation. The discovery of a sub-brown dwarf with an orbiting planet is also mentioned as an example. This type of planetary-mass object is not gravitationally bound to any star and is formed through the collapse of a gas cloud, rather than accretion or core collapse from a circumstellar disc. This concept is further explained through references to Science Daily and Wikipedia articles on rogue planets and sub-brown dwarfs.
  • #1
has anyone ever done research on the accretion of planets into a system without a star forming? Just a dark system. How likely is this to happen as opposed to a system forming with a star?
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  • #2
..what would the planets orbit?
  • #3
Central body can be massive, but it can be not massive enough to become a star. Like a brown dwarf (check wikipedia article). See also wiki entry on Cha 110913-773444.
  • #4
As Borek noted, planet formation does not require a star. An oversized 'Jupiter' would be sufficient. I expect any such planets would, however, be small.
  • #5
"David Bennett of the University of Notre Dame has discovered an extra-solar planet of about three Earth masses orbiting a star with a mass so low that its core may not be large enough to maintain nuclear reactions"

I noticed this on Science Daily this morning.
  • #6
Wikipedia said:
A rogue planet is an object which has equivalent mass to a planet and is not gravitationally bound to any star, and that therefore moves through space as an independent object.

Sub-brown dwarf is a planetary-mass object whose mass is smaller than the low-mass cut-off for brown dwarfs (around 13 times the mass of Jupiter). Unlike proper brown dwarfs, they are not massive enough to fuse deuterium. Sub-brown dwarfs are formed in the manner of stars, through the collapse of a gas cloud, and not through accretion or core collapse from a circumstellar disc.
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