Suppression of x-rays during an optical outburst of the helium dwarf nova kl dra

Gavin Ramsay, Peter J Wheatley, Simon Rosen, Thomas Barclay, Danny Steeghs

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KL Dra is a helium-accreting AM CVn binary system with an orbital period close to 25min. Approximately every 60d there is a 4-mag optical outburst lasting ∼10d. We present the most sensitive X-ray observations made of an AM CVn system during an outburst cycle. A series of eight observations were made using XMM-Newton which started shortly after the onset of an optical outburst. We find that X-rays are suppressed during the optical outburst. There is some evidence for a spectral evolution of the X-ray spectrum during the course of the outburst. A periodic modulation is seen in the ultraviolet data at three epochs - this is a signature of the binary orbital or the superhump period. The temperature of the X-ray-emitting plasma is cooler compared to dwarf novae, which may suggest that a wind is the origin of a significant fraction of the X-ray flux.

Original languageEnglish
Pages (from-to)1486-1491
Number of pages6
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Publication statusPublished - 11 Sept 2012
Externally publishedYes


  • Accretion, accretion discs
  • Binaries: general
  • Novae, cataclysmic variables
  • Stars: dwarf novae
  • Stars: individual: KL Dra
  • X-rays: stars

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