Query : 2002MNRAS.337.1215N

2002MNRAS.337.1215N - Mon. Not. R. Astron. Soc., 337, 1215-1223 (2002/December-3)

The systemic velocities of four long-period cataclysmic variable stars.


Abstract (from CDS):

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 (σγ ) 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/s with uncertainties of the order of 3 km/s, referred to the dynamical local standard of rest, leading to a dispersion of ∼8 km/s. Calculation of a 95 per cent confidence interval gives the result 4 < σγ< 28 km/s compared with a prediction of 15 km/s . We also have an improved determination of mass donor spectral type, K2 and q for the four systems.

Abstract Copyright: RAS

Journal keyword(s): accretion, accretion discs - techniques: radial velocities - binaries: spectroscopic - novae, cataclysmic variables

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 V* AH Her CV* 16 44 10.0057431264 +25 15 01.942541352   12.44 12.71     K2 229 0
2 V* V426 Oph CV* 18 07 51.6919772928 +05 51 47.804055084           ~ 164 0
3 V* EM Cyg CV* 19 38 40.1068970904 +30 30 28.332591012     11.90     ~ 248 0
4 V* SS Cyg CV* 21 42 42.8034497592 +43 35 09.867842484 11.07 12.651 12.032 9.326   K5V 1264 1

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