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 intermedia
te 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.
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 intermedia
te 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.
Long, linear areas of open water that range from a few meters to over a kilometer in width, and tens of kilometers long; they develop as ice diverges, or pulls apart.
A more than 50 m wide rectilinear or wedge-shaped crack from several kilometers to several hundreds of kilometers in length. At below freezing temperatures, new, nilas and young ice forms at the surfa
ce of leads.
Any fracture or passage-way through sea ice which is navigable by surface vessels. A more general description of a lead is an area of open water or new ice between ice floes, although the term is gene
rally applied to linear features. If the open area is very large it may be called a polynya. A lead between the shore and the pack ice is called a coastal lead or shore lead, and a lead between the fast ice and the pack ice is called a flaw lead.