Journal Article

2XMMi J225036.9+573154 – a new eclipsing AM Her binary discovered using <i>XMM–Newton</i>

Gavin Ramsay, Simon Rosen, Pasi Hakala and Thomas Barclay

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 395, issue 1, pages 416-421
Published in print May 2009 | ISSN: 0035-8711
Published online April 2009 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2009.14528.x
2XMMi J225036.9+573154 – a new eclipsing AM Her binary discovered using XMM–Newton

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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.

Keywords: binaries: close; stars: individual: 2XMMi J225036.9+573154; novae, cataclysmic variables; X-rays: binaries

Journal Article.  4153 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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