2009/01/22 by T. Sivarani, S. Lépine, A. K. Kembhavi +1 · 3 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Galactic halo #Halo #Proper motion #Radial velocity #Sky #Spectral signature #Stellar classification #Stellar, planetary, and galactic studies #Subdwarf #astro-ph.EP #astro-ph.SR
paper · pdf · doi:10.1088/0004-637x/694/2/l140
13 pages, 2 figures. Accepted for ApJL
arxiv created 2009/01/22 · openalex publication_date 2009/03/13 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We report the discovery of a high proper motion L subdwarf (μ = 0 617 yr −1 ) in the Sloan Digital Sky Survey (SDSS) spectral database. The optical spectrum from the star SDSS J125637–022452 has mixed spectral features of both late-M spectral subtype (strong TiO and CaH at 7000 Å) and mid-L spectral subtype (strong wings of KI at 7700 Å, CrH, and FeH), which is interpreted as the signature of a very low-mass, metal-poor star (ultracool subdwarf) of spectral-type sdL. The near-infrared (NIR) ( J − K s ) colors from 2MASS show the object to be significantly bluer compared to normal L dwarfs, which is probably due to a strong collision-induced absorption (CIA) from the H 2 molecule. This is consistent with the idea that CIA from H 2 is more pronounced at low metallicities. Proper motion and radial velocity measurements also indicate that the star is kinematically "hot" and probably associated with the Galactic halo population.