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The Question
(Submitted October 23, 1997)
Can you tell me the differences between exoplanets and brown dwarfs
please. Also I could not find any book regarding this. Is it because
brown dwarfs and exoplanets are new to us?
The Answer
This is somewhat outside our field of expertise (which is X-ray,
gamma-ray and cosmic ray astrophysics), but I've managed to find
a definition in the 'EXOPLANETS' pages at:
http://etacha.as.arizona.edu/~eem/exo.html (http://etacha.as.arizona.edu/%7Eeem/exo.html)
The difference is in how they formed: brown dwarfs formed through the
collapse of a molecular cloud, planets formed around a protostar
through accretion of planetesimals and gas.
I think the subject of (theoretical studies of, and searches for) brown
dwarfs and exoplanets have been with us for a long time. However, until
recently, we had had very little data --- it is only within the last few
years that many important discoveries have been made. So I think you are
basically correct as to why you cannot find books on these subjects.
Best wishes,
Koji Mukai
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