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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.
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