Astron. Astrophys. 332, 904-908 (1998)

BeppoSAX observations of the long period polar system V1309 Ori ^*

D. de Martino ¹, R. Barcaroli ², G. Matt ², M. Mouchet ^{3, 4}, T. Belloni ⁵, K. Beuermann ⁶, L. Chiappetti ⁷, C. Done ⁸, B.T. Gänsicke ⁶, F. La Franca ² and K. Mukai <sup>9

1</sup> Osservatorio Astronomico di Capodimonte, Via Moiariello 16, I-80131 Napoli, Italy
² Dipartimento di Fisica, Universita' degli studi "Roma Tre", Via della Vasca Navale 84, I-00146 Roma, Italy
³ DAEC, Observatoire de Paris, Section de Meudon, F-92195 Meudon Cedex, France
⁴ University Denis Diderot, Place Jussieu, F-75005 Paris, France
⁵ Astronomical Institute "Anton Pannekoek", University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
⁶ Universitäts Sternwarte, Geismarlandstr. 11, D-37083 Göttingen, Germany
⁷ Istituto di Fisica Cosmica CNR, Via Bassini 15, Milano, Italy
⁸ Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK
⁹ NASA/GSFC, Code 668 Greenbelt MD 20771, USA

Received 22 October 1997 / Accepted 6 January 1998

Abstract

We present BeppoSAX observations of the peculiar long period polar system V1309 Ori (RXJ0515.6+0105). The source was detected simultaneously at soft and, for the first time, at hard X-rays with the LECS and the MECS detectors. Both, the LECS and the MECS light curves are irregular with a bursting/flaring type behaviour indicating inhomogeneous accretion onto the white dwarf. This peculiar variability, together with an extreme high soft-to-hard X-ray luminosity ratio, indicates that in V1309 Ori accretion occurs predominantly in highly compressed chunks or "blobs" of matter. From coordinated ESO optical spectroscopy, we find indications that the magnetic field strength of the white dwarf is 70 MG, not expected either from the 8 hr orbital period synchronism or from the strong soft-to-hard X-ray ratio suggesting alternative solutions for sustaining synchronism in this system.

Key words: stars: individual: V1309 Ori= RXJ0515.6+0105 cataclysmic variables X-rays: stars

* Also based on observations collected at the European Southern Observatory, La Silla, Chile

Send offprint requests to: D. de Martino

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Contents

• 1. Introduction
• 2. BeppoSAX observations
  • 2.1. The X-ray light curves
  • 2.2. The X-ray spectrum
• 3. The optical observations
• 4. Discussion and conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 1998

Online publication: March 30, 1998
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