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Astron. Astrophys. 329, 571-578 (1998)

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Insights into the accretion flow in QS Telescopii (RE1938-461)
from HST observations *

D. de Martino 1, M. Mouchet 2, 3, S.R. Rosen 4, B.T. Gänsicke 5, K.L. Clayton 4 and K.O. Mason 4

1 Osservatorio Astronomico di Capodimonte, Via Moiariello 16, I-80131 Napoli, Italy
2 DAEC, Observatoire de Paris, Section de Meudon, F-92195 Meudon Cedex, France
3 University Denis Diderot, Place Jussieu, F-75005 Paris, France
4 Department of Physics and Astronomy, University of Leicester, University Rd., Leicester, LE1 7RH, UK
5 Universitäts Sternwarte, Geismarlandstr. 11, D-37083 Göttingen, Germany

Received 4 April 1997 / Accepted 19 August 1997


We present HST/FOS observations of the polar QS Tel (RE1938-461) revealing new details in its 140 min UV orbital variability. A colour-dependent continuum orbital modulation as well as a narrow dip in its light curve, occurring at the same orbital phases as the one detected in the EUVE band, are observed. Their spectral dependence allows us to identify the heated regions of the white dwarf surface with complex structure and temperature gradients as well as the accretion stream. The absorption dip occurs during the minimum of UV emission line light curves and is interpreted as the occultation of the heated spot on the white dwarf surface by the accretion stream. We also confirm the strong UV modulation of the emission lines which, in these high time resolved spectroscopic data, is structured and consistent with X-ray irradiation of the stream material.

Key words: stars: cataclysmic variables – ultraviolet: stars – stars: individual: QS Tel

* Based on observations collected with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute

Send offprint requests to: D. de Martino

© European Southern Observatory (ESO) 1998

Online publication: December 8, 1997