2003/05/19 by H. C. Harris, Hugh C. Harris, J. Liebert +63 · 3 citations
Physics and Astronomy · #Astrophysics and Star Formation Studies #Gamma-ray bursts and supernovae #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/376842
published as Astron.J. 126 (2003) 1023 · Accepted for AJ; 43 pages, including 12 figures and 5 tables
arxiv created 2003/05/19 · openalex publication_date 2003/07/31 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
An initial assessment is made of white dwarf and hot subdwarf stars observed in the Sloan Digital Sky Survey. In a small area of sky (190 square degrees), observed much like the full survey will be, 269 white dwarfs (WDs) and 56 hot subdwarfs are identified spectroscopically where only 44 white dwarfs and five hot subdwarfs were known previously. Most are ordinary DA (hydrogen atmosphere) and DB (helium) types. In addition, in the full survey to date, a number of WDs have been found with uncommon spectral types. Among these are blue DQ stars displaying lines of atomic carbon; red DQ stars showing molecular bands of C 2 with a wide variety of strengths; DZ stars where Ca and occasionally Mg, Na, and/or Fe lines are detected; and magnetic WDs with a wide range of magnetic field strengths in DA, DB, DQ, and (probably) DZ spectral types. Photometry alone allows identification of stars hotter than 12,000 K, and the density of these stars for 15 < g < 20 is found to be ∼2.2 deg -2 at Galactic latitudes of 29°–62°. Spectra are obtained for roughly half of these hot stars. The spectra show that for 15 < g < 17, 40% of hot stars are WDs, and the fraction of WDs rises to ∼90% at g = 20. The remainder are hot sdB and sdO stars.