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EUVE Spectrophotometry of QS Tel: The Second Pole Becomes Active

Published online by Cambridge University Press:  12 April 2016

S.R. Rosen ,
J.P.D. Mittaz ,
D.A.H. Buckley ,
A. Layden ,
C. McCain ,
J.P. Osborne  and
M.G. Watson
S.R. Rosen
Affiliation:
Department of Physics, University of Leicester, University Rd., Leicester, LEI 7RH, UK
J.P.D. Mittaz
Affiliation:
Mullard Space Science Laboratory, Holmbury St. Mary, Surrey, RH5 6NT, UK
D.A.H. Buckley
Affiliation:
South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa
A. Layden
Affiliation:
Cerro Tololo Inter-American Observatory, Casilla 603, La Serena, Chile
C. McCain
Affiliation:
Mt. Stromlo and Siding Spring Observatories, Weston Creek, PO, ACT 2611, Australia
J.P. Osborne
Affiliation:
Department of Physics, University of Leicester, University Rd., Leicester, LEI 7RH, UK
M.G. Watson
Affiliation:
Department of Physics, University of Leicester, University Rd., Leicester, LEI 7RH, UK

Abstract

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We present results of EUVE spectrophotometry of the EUV luminous polar, QS Tel (RE1938-461), together with contemporaneous optical photometry and spectroscopy. In marked contrast to the ROSAT survey observations, the EUVE light curve shows two flux maxima per orbital cycle, implying that both magnetic poles were active. A deep, narrow dip is observed during one of the two flux maxima, exhibiting a complex morphology which includes pronounced flickering behaviour. Although this feature is probably caused by stream occultation of the emission region, the apparent lack of spectral hardening at this time disfavours photoelectric absorption by cold gas as the dominant source of opacity. Whilst the overall EUVE spectrum can be characterized by a low temperature (~15eV) blackbody, implying a large soft/hard component flux ratio (~50), tentative evidence of an absorption edge from NeVI at 85A and lines due to NeVIII and NeVII at 98Å and 116Å respectively indicate that more sophisticated models must be employed. Quasi-simultaneous optical photometry shows a substantial change in the light curve over an interval of just 3 days and little evidence of correlated behaviour with the EUV flux. We consider the implications of these results on the accretion geometry and the structure of the accretion flow.

Type
VI. Cataclysmic Variable Stars
Information
International Astronomical Union Colloquium , Volume 152: Astrophysics in the Extreme Ultraviolet , 1996 , pp. 331 - 335
Copyright
Copyright © Kluwer 1996

References

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