A brown dwarf is a term used to describe objects whose mass is too insufficient for the development of a star with a hydrogen-burning core
but which is sufficiently large to be dismissed as a (large gaseous) planet. Typically such entities are characterized with masses less than
0.07 to 0.09 solar masses and are associated with low magnitudes (no nuclear fusion!) and emissions usually in the infrared portion of the
spectrum. In fact, dwarfs are more closely related to planets due to the fact their mass is expressed in multiples of Jupiter's mass (ex.
70 Jupiter masses) and perhaps may represent failed stars. The IAU has defined a brown dwarf to be any substellar object whose mass is at
least 13 Jupiters while those objects below this limit are considered planets.
Dwarfs are classified by their absorption spectrum of various metals and which includes M, L and T groupings. M-class dwarfs are dominant in the visible portion of the spectrum and whose temperatures exceed 2100 degrees Kelvin; L-class dwarfs are dominant in the red portion of the spectrum and are cooler (1,500 to 2,100 degrees Kelvin); and T-class dwarfs are dominant near the infra-red portion of the spectrum with absorption by methane and water and the coolest of all brown dwarfs (800 to 1000 degrees Kelvin).
The first brown dwarf to be discovered was Gliese 229b (1995) in the constellation of Lepus and which also happens to be a binary brown dwarf. The closest known brown dwarfs are Epsilon Indi Ba and Bb in the constellation of Indus lying at a distance of only 3.626 pc (11.82 light-years). The coolest known brown dwarf with a temperature of only 600-700K is ULAS J0034-00 in Cetus and which was discovered in 2007. It is characterized with a mass of only 15 to 30 times that of Jupiter and lies 50 light-years away. More recently, the WISE mission identified its first 100 brown dwarfs comprised of one M dwarf, eight L dwarfs, eighty-nine T dwarfs and six Y dwarfs.
Note: The brown dwarf LSR 0602+3910 in Auriga illustrated below was originally identified as a star by Lepine (2002) characterized with high proper motion while studying plates from the Digitized Sky Survey. Further analysis by Salim (2003) confirmed this object to be a brown dwarf of type L with probably no apparent binary component. LSR 0602+3910 lies approximately 10 parsecs (34.6 light-years) away and is amongst the eight closest brown dwarfs to our sun. For a finder chart from Lepine's original paper, click here.
Please click on the image below to display in higher resolution (800 x 600)
RA / Dec:
06h 02m 30s /
+39° 10' 59"
10.6 + 0.8 pc
Dec 07-08, 2007
23:35 - 02:10 UT+2
AP 160 f/7.5 StarFire EDF
SBIG LRGB filters
Baader 685nm IR Pass