2007/01/29 by Adam J. Burgasser, Burgasser, Adam J.
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #Astrophysics and Star Formation Studies #FOS: Physical sciences #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0701793
5 pages, 4 figures, contribution to proceedings for the 14th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun, 6-10 November 2006
arxiv created 2007/01/29 · openalex publication_date 2007/01/29 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
In the past few years, astronomers have uncovered several very low-temperature, metal-poor stars with halo or thick disk kinematics and peculiar spectral and photometric properties, so-called ultracool subdwarfs. These include the first examples of L subdwarfs - metal-poor analogs of the L dwarf spectral class - and slightly metal-deficient T dwarfs. Ultracool subdwarfs provide useful empirical tests of low temperature atmosphere and evolutionary models, and are probes of the halo mass function down to and below the (metal-dependent) hydrogen burning limit. Here I summarize the optical and near-infrared spectroscopic properties of these objects, review recent research results, and point out scientific issues of interest in this developing subject.