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Astron. Astrophys. 340, 129-134 (1998)

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RX J1016.9-4103: a new soft X-ray polar in the period gap *

Jochen Greiner and Robert Schwarz

Astrophysical Institute Potsdam, An der Sternwarte 16, D-14482 Potsdam, Germany

Received 18 August 1998 / Accepted 14 September 1998


We have discovered a new AM Her system as the optical counterpart of the ROSAT All-Sky-Survey source RX J1016.9-4103 ([FORMULA] 1RXS J101659.4-410332). The X-ray spectrum is very soft and the X-ray intensity is strongly modulated with the orbital period. Optical photometric and spectroscopic follow-up observations reveal a synchronously rotating binary with an orbital period of 134 min, placing RX J1016.9-4103 in the period gap. The strength of the TiO bands suggests a secondary spectral type later than M3 V and a distance of 615[FORMULA]150 pc. Based on two clearly visible broad humps in the optical spectrum (interpreted as cyclotron features) a magnetic field strength of 52 MG is deduced thus proving the polar classification.

Key words: stars: individual: RXJ 1016.9-4103 – novae, cataclysmic variables – X-rays: stars

* Partly based on observations collected during MPI time at the 2.2 m telescope of the European Southern Observatory, La Silla, Chile.

Send offprint requests to: Greiner, (jgreiner@aip.de)

© European Southern Observatory (ESO) 1998

Online publication: November 3, 1998