Open AccessThe intermediate‐age brown dwarf LP 944‐20
Author(s) -
C. G. Tinney
Publication year - 1998
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1998.01642.x
Subject(s) - physics , brown dwarf , pleiades , astrophysics , luminosity , equivalent width , proper motion , stellar classification , astronomy , spectral line , emission spectrum , stars , galaxy
Observations are presented which show that Li I λ 6708 is detected with an equivalent width of 0.53 ± 0.05Å in the proper‐motion object LP 944‐20 (which is also known as BRI 0337‐3535). Hα is detected in emission at an equivalent width of 1.2 ± 0.5Å. The detection of Li implies a mass less than 0.065 M⊙, making this object a brown dwarf. Moreover, the relative weakness of this Li detection (compared to the equivalent widths of 1–2Å seen in objects of similar spectral type in the Pleiades) implies that Li has been somewhat depleted. This, together with the precisely determined luminosity of LP 944‐20, implies a mass between 0.056 and 0.064 M⊙, and age between 475 and 650 Myr. This makes it the first brown dwarf to have a well‐constrained mass and age determined.