2007/08/02 by Andrew G. Cantrell, Charles D. Bailyn
Physics and Astronomy · #Accretion (finance) #Accretion disc #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Binary number #Binary star #Neutron star #Offset (computer science) #Radial velocity #Stars #astro-ph
paper · pdf · doi:10.1086/522084
38 pages, 3 figures, to be published in ApJ
arxiv created 2007/08/02 · openalex publication_date 2007/11/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Radial velocity studies of accreting binary stars commonly use accretion disk emission lines to determine the radial velocity of the primary star and therefore the mass ratio. These emission-line radial velocity curves are often shifted in phase from the expected motion of the primary. These phase shifts cast doubt on the use of disk emission lines in the determination of mass ratios. We present a systematic study of phase shifts, using data from the literature to distinguish between possible explanations of the phase shift. We find that one widely adopted class of models is contradicted by observations. We present a generalized form of another class of models, which we call "measurement-offset models." We show that these models are quantitatively consistent with existing data. We consider the implications of adopting measurement-offset models, for both disk structure and determination of binary parameters. Specifically, we describe how measurement-offset models may be used improve determinations of the mass ratio based on disk emission lines. This could be a valuable new tool in determining masses of important astrophysical objects such as accreting neutron stars and black holes.