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The Rotational Velocity of Helium-rich Pre-White Dwarfs

T. Rauch·S. Koeper·S. Dreizler·K. Werner·U. Heber·I. N. Reid
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Abstract

Previous investigations on hydrogen-rich white dwarfs generally yield only very small rotational velocities (v_rot sin i). We have analyzed line profiles in high-resolution optical spectra of eight hydrogen-deficient (pre-) white dwarfs and find deviations from the dominant Stark line broadening in five cases which, interpreted as an effect of stellar rotation, indicate projected rotational velocities of 40 - 70 km/sec. For the three least luminous stars upper limits of v_rot sin i = 15 - 25 km/sec could be derived only. The resulting velocities correlate with luminosity and mass. However, since the mass-loss rate is correlated to the luminosity of a star, the observed line profiles may be affected by a stellar wind as well. In the case of RX J2117.1+3412, this would solve discrepancies to results of pulsational modeling (v_rot sin i ~ 0).

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T. Rauch, S. Koeper, S. Dreizler, K. Werner, U. Heber, I. N. Reid. 2002-12-06. The Rotational Velocity of Helium-rich Pre-White Dwarfs. https://arxiv.org/abs/astro-ph/0212163

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