A new, EUV-bright intermediate polar discovered in the ROSAT Wide Field Camera all-sky survey

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Abstract
A new intermediate polar (IP) has been found during a programme of optical identification of extreme-ultraviolet sources from the ROSAT Wide Field Camera all-sky survey. The new IP, RE0751 + 14, is the first EUV-selected object of its type and only the second such star to have been detected in the extreme ultraviolet. There is evidence that the EUV flux in RE0751 + 14 comes from a soft spectral component which is distinct from the hard X-ray emission. RE0751 + 14 is also unusual in showing a complex modulation profile at the inferred spin period of the white dwarf star, 13.9 min. This is evident both in the infrared, and in the X-ray light curve measured using the Ginga satellite. The 13.9-min X-ray light curve is made up of two distinct components which are out of phase: a quasi-sinusoidal modulation which is energy independent, and a narrower ‘dip’ component which increases in depth towards low energies. These two components may be identified as, respectively, obscuration of the emission region by the white dwarf, and absorption of radiation by the accretion stream. If so, RE0751 + 14 contains elements of both competing models that have been advanced to explain the spin modulation in intermediate polars.

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