Discovery of the high-field polar RX J1724.0+4114 |
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| Authors: | Jochen Greiner Robert Schwarz & Wolfgang Wenzel |
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| Institution: | Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany,;96515 Sonneberg, Hauptstrasse 40, Germany |
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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 He II 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 yr reveal a period of 119.9 min, directly 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 on the distance of d ≳ 250 pc. |
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| Keywords: | accretion accretion discs stars: individual: RX J1724 0+4114 stars: magnetic fields novae cataclysmic variables |
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