EDP Sciences
Free Access
Volume 374, Number 2, August I 2001
Page(s) 656 - 661
Section Formation, structure and evolution of stars
DOI https://doi.org/10.1051/0004-6361:20010787
Published online 15 August 2001

A&A 374, 656-661 (2001)
DOI: 10.1051/0004-6361:20010787

HST/STIS spectroscopy of the exposed white dwarf in the short-period dwarf nova EK TrA

B. T. Gänsicke1, P. Szkody2, E. M. Sion3, D. W. Hoard4, S. Howell5, F. H. Cheng3 and I. Hubeny6

1  Universitäts-Sternwarte, Geismarlandstr. 11, 37083 Göttingen, Germany
2  Department of Astronomy, Box 351580, University of Washington, Seattle, WA 98195, USA
3  Department of Astronomy & Astrophysics, Villanova University, Villanova, PA 19085, USA
4  Cerro Tololo Inter-American Observatory, Casilla 603, La Serena, Chile
5  Astrophysics Group, Planetary Science Institute, 620 North 6th Avenue, Tucson, AZ 85705, USA
6  Laboratory for Astronomy and Solar Physics, NASA/GSFC, Greenbelt, MD 20711, USA

(Received 3 April 2001 / Accepted 28 May 2001 )

We present high resolution Hubble Space Telescope ultraviolet spectroscopy of the dwarf nova EK TrA obtained in deep quiescence. The Space Telescope Imaging Spectrograph data reveal the broad ${\rm Ly\alpha}$ absorption profile typical of a moderately cool white dwarf, overlayed by numerous broad emission lines of He, C, N, and Si and by a number of narrow absorption lines, mainly of CI and SiII. Assuming a white dwarf mass in the range 0.3-1.4 $M_{\odot}$ we derive $T_{\rm eff}=17 500$-23 400 K for the primary in EK TrA; $T_{\rm eff}=18 800$ K for a canonical mass of 0.6 $M_{\odot}$. From the narrow photospheric absorption lines, we measure the white dwarf rotational velocity, $v\sin i=200\pm100$ $\rm km s^{-1}$. Even though the strong contamination of the photospheric white dwarf absorption spectrum by the emission lines prevents a detailed quantitative analysis of the chemical abundances of the atmosphere, the available data suggest slightly sub-solar abundances. The high time resolution of the STIS data allows us to associate the observed ultraviolet flickering with the emission lines, possibly originating in a hot optically thin corona above the cold accretion disk.

Key words: accretion, accretion disks -- stars: individual: EK TrA -- stars: novae, cataclysmic variables -- stars: white dwarfs -- ultraviolet: stars

Offprint request: B. T. Gänsicke, boris@uni-sw.gwdg.de

SIMBAD Objects

© ESO 2001

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.