2XMMi J225036.9+573154 – a new eclipsing AM Her binary discovered using XMM–Newton |
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| Authors: | Gavin Ramsay Simon Rosen Pasi Hakala Thomas Barclay |
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| Institution: | Armagh Observatory, College Hill, Armagh BT61 9DG;Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH;Tuorla Observatory, University of Turku, Väisäläntie 20, FIN-21500 Piikkiö, Finland;MullardIsaac Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT |
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| Abstract: | We report the discovery of an eclipsing polar, 2XMMi J225036.9+573154, using XMM–Newton . It was discovered by searching the light curves in the 2XMMi catalogue for objects showing X-ray variability. Its X-ray light curve shows a total eclipse of the white dwarf by the secondary star every 174 min. An extended pre-eclipse absorption dip is observed in soft X-rays at φ= 0.8–0.9 , with evidence for a further dip in the soft X-ray light curve at φ∼ 0.4 . Further, X-rays are seen from all orbital phases (apart from the eclipse) which make it unusual amongst eclipsing polars. We have identified the optical counterpart, which is faint ( r = 21) , and shows a deep eclipse (>3.5 mag in white light). Its X-ray spectrum does not show a distinct soft X-ray component which is seen in many, but not all, polars. Its optical spectrum shows Hα in emission for a fraction of the orbital period. |
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| Keywords: | binaries: close stars: individual: 2XMMi J225036 9+573154 novae cataclysmic variables X-rays: binaries |
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