An Etymological Dictionary of Astronomy and Astrophysics

A type of → brown dwarf with an → effective temperature ranging from about 2200 K to about 1300 K, corresponding to luminosities about 4 x 10^-4 to 3 x 10^-5 times that of the Sun. L dwarfs are intermediate in temperature between M and → T dwarfs. Their spectra in the optical show weak titanium oxide (TiO) and vanadium oxide (VO) absorption lines and strong metallic hydrides CrH (8611 and 9969 Å) and FeH (8692 and 9896 Å). Also are present strong neutral atomic lines of alkali metals Na I (8183, 8195 Å), K I (7665, 7699 Å), Rb I (7800, 7948 Å), Cs I (8521, 8943 Å), and sometimes Li I (6708 Å). The prototype of the L-dwarf class is → GD 165B. The spectral classification was first defined by Kirkpatrick et al. 1999, ApJ 519, 802 and Martin et al. 1999, AJ 118, 2466.

See also: For the reasoning behind the choice of the letter L, see Kirkpatrick et al. 1993, ApJ 406, 701; → dwarf.