2006/11/30 by Mukremin Kilic, Carlos Allende Prieto, Warren R. Brown +1 · 93 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Binary number #Black dwarf #Blue dwarf #Brown dwarf #Low Mass #Radial velocity #Stellar classification #Stellar, planetary, and galactic studies #White dwarf #astro-ph
paper · pdf · doi:10.1086/514327
published in The Astrophysical Journal 660(2), 1451-1461 (IOP Publishing) · ApJ, accepted version
arxiv created 2007/02/13 · openalex publication_date 2007/05/04 · arxiv updated 2011/02/11 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Extremely low mass white dwarfs are very rare objects likely formed in compact binary systems. We present MMT optical spectroscopy of 42 low-mass white dwarf candidates serendipitously discovered in a survey for hypervelocity B-type stars. One of these objects, SDSS J0917+46, has T eff = 11,288 ± 72 K and log g = 5.48 ± 0.03; with an estimated mass of 0.17 M ☉ , it is the lowest gravity/mass white dwarf currently known. However, 40 of the low-mass candidates are normal DA white dwarfs with apparently inaccurate SDSS g magnitudes. We revisit the identification of low-mass white dwarf candidates previously found in the SDSS and conclude that four objects have M < 0.2 M ☉ . None of these white dwarfs show excess emission from a binary companion, and radial velocity searches will be necessary to constrain the nature of the unseen companions.