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The Rotational Velocity of Helium-rich Pre-White Dwarfs

Published online by Cambridge University Press:  26 May 2016

Thomas Rauch ,
Sebastian Köper ,
Stefan Dreizler ,
Klaus Werner ,
Ulrich Heber  and
I. Neill Reid
Thomas Rauch
Affiliation:
Dr.-Remeis-Sternwarte, D-96049 Bamberg, Germany Institut für Astronomie und Astrophysik, D-72076 Tübingen, Germany
Sebastian Köper
Affiliation:
Institut für Astronomie und Astrophysik, D-72076 Tübingen, Germany
Stefan Dreizler
Affiliation:
Institut für Astronomie und Astrophysik, D-72076 Tübingen, Germany
Klaus Werner
Affiliation:
Institut für Astronomie und Astrophysik, D-72076 Tübingen, Germany
Ulrich Heber
Affiliation:
Dr.-Remeis-Sternwarte, D-96049 Bamberg, Germany
I. Neill Reid
Affiliation:
STScI, Baltimore, MD, USA

Abstract

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Previous investigations on hydrogen-rich white dwarfs generally yield only very small rotational velocities (v 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 s–1. For the three least luminous stars upper limits of v sin i = 15 – 25 km s–1 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 sin i ≈ 0).

Type
Session 5 Final Stages, Nucleosynthesis
Information
Symposium - International Astronomical Union , Volume 215: Stellar Rotation , 2004 , pp. 573 - 574
Copyright
Copyright © Astronomical Society of the Pacific 2004 

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