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The systemic velocities of four long-period cataclysmic variable stars

North, R.C.; Marsh, T.R.; Kolb, U.; Dhillon, V.S. and Moran, C.K.J. (2002). The systemic velocities of four long-period cataclysmic variable stars. Monthly Notices of the Royal Astronomical Society, 337(4) pp. 1215–1223.

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Although a large number of orbital periods of cataclysmic variable (CV) stars have been measured, comparison of period and luminosity distributions with evolutionary theory is affected by strong selection effects. A test has been discovered that is independent of these selection effects and is based upon the kinematics of CVs. If the standard models of evolution are correct then long-period (Porb > 5 h) CVs should be typically less than 1.5 Gyr old, and their line-of-sight velocity dispersion (σ) should be small. We present results from a pilot study, which indicate that this postulate is indeed true. Four long-period dwarf novae (EM Cyg, V426 Oph, SS Cyg and AH Her) were observed over a complete orbit, in order for accurate radial velocities to be obtained. We find values of −1.7, 5.4, 15.4 and 1.8 km s1 with uncertainties of the order of 3 km s1, referred to the dynamical local standard of rest, leading to a dispersion of 8 km s1. Calculation of a 95 per cent confidence interval gives the result 4 <σ < 28 km s1 compared with a prediction of 15 km s1. We also have an improved determination of mass donor spectral type, K2 and q for the four systems.

Item Type: Journal Item
Copyright Holders: 2002 The Royal Astronomical Society
ISSN: 1365-2966
Keywords: accretion; accretion discs; techniques; radial velocities; binaries; spectroscopic; novae; cataclysmic variables
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Item ID: 4492
Depositing User: Users 6827 not found.
Date Deposited: 06 Jul 2006
Last Modified: 07 Dec 2018 08:56
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