Spectrally resolved eclipse maps of the accretion disk in UX Ursae Majoris

Abstract

ACCRETION disks play an important role in many astrophysical environments, such as active galactic nuclei, protostellar systems, X-ray binaries and cataclysmic variables. The lack of spatially resolved information, however, has meant that theoretical models for accretion disks are in general poorly constrained by observations. Here we use the shape of the light curves from an eclipsing cataclysmic variable, UX Ursae Majoris, to reconstruct the spectral energy distribution (in the range 3,600–10,000 Å) across the face of an accretion disk. The spectral resolution is sufficient to reveal both the radial dependence of absorption and emission line features within the disk, and the spectral details of the bright spot formed at the point where the accretion stream from the secondary star collides with the disk. Such detailed reconstructions of accretion-disk spectra should help to bridge the gap between observations and theoretical models.