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Astron. Astrophys. 333, 540-546 (1998)

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Optical and X-ray study of MS1603+2600 *

P.J. Hakala 1, 2, D.H. Chaytor 4, O. Vilhu 1, V. Piirola 3, S.L.Morris 4 and P. Muhli 1

1 Observatory and Astrophysics Laboratory, P.O. Box 14, FIN-00014 University of Helsinki, Finland
2 Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking RH5 6NT, Surrey, UK
3 Tuorla Observatory, FIN-21500 Piikkio, Finland
4 Dominion Astrophysical Observatory, National Research Council, 5071 West Saanich Road, Victoria, B.C., V8X 4M6, Canada

Received 23 June 1997 / Accepted 21 November 1997


We present results from [FORMULA] years of optical monitoring of an unusual interacting compact binary MS1603+2600 together with the results of ROSAT observations. Our CCD-photometry confirms the erratic behaviour of the optical light curve shape reported by Morris et al. (1990). The ROSAT-PSPC observations suggest that MS1603 might be a short period soft X-ray transient (SXT) never seen in outburst. This would probably require, that the compact object in MS1603 is a black hole rather than a neutron star. In addition to optical photometry and ROSAT data, we present first circular polarimetric observations of the source and discuss the nature and origin of MS1603+2600.

Key words: stars: individual: MS1603+2600 – stars: binaries, close – accretion

* Based on optical observations made at the Nordic Optical Telescope, La Palma

Send offprint requests to: P.J. Hakala

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© European Southern Observatory (ESO) 1998

Online publication: April 20, 1998