AAS 196th Meeting, June 2000 Session 20. Stellar Populations
Invited, Monday, June 5, 2000, 3:40-5:10pm, Lilac Ballroom
[Previous] | [Session 20] | [Next]  [20.02] What We Have Learned
about L and T Dwarfs  J. D. Kirkpatrick (IPAC/Caltech)  In 1901,
Annie Jump Cannon gave us the OBAFGKM spectral sequence with
which we are all familiar. One hundred years later, a change of
the main sequence types to OBAFGKMLT is now proposed so that
objects even cooler than M dwarfs can be included.  Just a few
short years ago - in 1997, in fact - the lower end of the main
sequence was populated by a handful of late-M dwarfs and two
other objects, GD 165B and Gl 229B. Dismissed at the time by
many researchers as a freak unrelated to normal stars or brown
dwarfs, GD 165B has instead proven to be the prototype of a new
spectral class, called ``L dwarfs'', which is just cooler than
class M and encompasses both low-mass stars and warm brown
dwarfs. Likewise the methane dwarf Gl 229B, heralded as the
first bona fide brown dwarf di