2006/08/04 by J. R. Thorstensen, John R. Thorstensen, Sébastien Lépine +3 · 1 citation
Engineering · Physics and Astronomy · #Astrometry #Astronomical Observations and Instrumentation #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Be star #Cataclysmic variable star #Emission spectrum #Galaxy #Orbital period #Parallax #Photometry (optics) #Physics #Proper motion #ROSAT #Radial velocity #Spectral line #Stars #Stellar, planetary, and galactic studies #White dwarf #astro-ph
paper · pdf · doi:10.1086/507956
14 pages, 3 figures; Publications of the Astronomical Society of the Pacific, in press
arxiv created 2006/08/04 · openalex publication_date 2006/09/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
RBS ( ROSAT Bright Source) 0490 is a cataclysmic variable star (CV) with unusually strong emission lines. The strength of the emission lines has led to a suggestion that the object is intrinsically faint and correspondingly nearby (∼33 pc), which, if true, would strongly affect estimates of the CV space density. Here we report astrometry, filter photometry, and time‐series spectroscopy of this object. The astrometry gives an absolute parallax π abs = 4.5 ± 1.5 mas and a relative proper motion of 102 mas yr −1 . A Bayesian procedure gives a very uncertain distance estimate of d∼300 pc, and the small parallax alone implies d>133 pc (at 2 standard deviations). The mean V magnitude is 17.4, which implies M V = 10.9 - 5log [d/(200 pc)], neglecting extinction. At 200 pc, the space velocity would be over 90 km s −1 with respect to the local standard of rest. The time‐series spectroscopy shows a possible emission‐line radial velocity period near 46 minutes. This would be unusually short for an orbital period, and it may represent some other clock in the system.