The mass of the white dwarf in GW libra

Abstract

We report a mass and rotational broadening (vsin i) for the pulsating white dwarf (WD) component of the WZSge type Dwarf Nova GW Lib based on high-resolution Very Large Telescope spectroscopy that resolves the Mg II 4481 Å absorption feature. Its gravitational redshift combined with WD mass-radius models provides us with a direct measurement of the WD mass of M 1 = 0.84 ± 0.02 M 1. The line is clearly resolved and if associated with rotational broadening gives vsin i = 87.0 ± 3.4 km s-1, equivalent to a spin period of 97 ± 12 s. © 2010 The American Astronomical Society. All rights reserved.