1997/01/15 by Axel D. Schwope, A. Schwope, Schwope, Axel D. +6
Physics and Astronomy · #Astrophysical Phenomena and Observations #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/9701087
4 pages, 3 postscript figures, Astron. Astrophysics, in press see also http://www.aip.de:8080/science/Preprints.html
arxiv created 1997/01/15 · openalex publication_date 1997/01/15 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present phase-resolved spectroscopy of the eclipsing AM Herculis star UZ For obtained when the system was in its low state of accretion. Faint residual Halpha-emission and NaI absorption were used to trace the secondary star and infer its orbital velocity K2. The measured radial velocity amplitude of NaI K2 * sin(i) = 285 ± 50 kmps suggests a low-mass white dwarf with Mwd = 0.44 ± 0.15 Msun (1 sigma-errors). The Halpha emission line on the other hand, visible only for part of the orbital cycle and supposed to originate only on the illuminated hemisphere facing the white dwarf, displays a similar radial velocity amplitude, K'2 sin(i) = 308 ± 27 kmps. The standard K2-correction applied by us then suggests a white dwarf mass of up to 1 Msun. Compared with earlier results the new ones enlarge the window in which the white dwarf mass may lie and resolves the conflict between mass estimates based on photometry and spectroscopy. They leave some ambiguity in the location of emission and absorption components in these and former observations.