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Discovery of the high-field polar RX J1724.0+4114

Jochen Greiner·Robert Schwarz·Wolfgang Wenzel
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Abstract

We report the discovery of a new AM Herculis binary (polar) as the optical counterpart of the soft X-ray source RX J1724.0+4114 detected during the ROSAT all-sky survey. The magnetic nature of this V~17 mag object is confirmed by low-resolution spectroscopy showing strong Balmer and HeII emission lines superimposed on a blue continuum which is deeply modulated by cyclotron humps. The inferred magnetic field strength is 50+/-4 MG (or possibly even ~70 MG). Photometric observations spanning ~3 years reveal a period of 119.9 min, right below the period gap. The morphology of the optical and X-ray light curves which do not show eclipses by the secondary star, suggests a self-eclipsing geometry. We derive a lower limit of d~250 pc.

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Jochen Greiner, Robert Schwarz, Wolfgang Wenzel. 1997-11-24. Discovery of the high-field polar RX J1724.0+4114. https://doi.org/10.1046/j.1365-8711.1998.01469.x

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