2001ApJ...553L.177D

Time-resolved, optical spectrophotometric observations of the Hα emission line in the cataclysmic variable V442 Oph are presented, and a long-term orbital ephemeris is derived. A method designed to quantify and locate the line-flickering activity in accretion disks is proposed on the basis of Doppler tomography techniques, and the line profile variability is explored. We found that the stochastic emission-line fluctuations in this system are the result of flaring activity at specific locations in the accretion disk. Such activity seems to be inhibited or damped for intrinsic gas velocities below 250 km.s^–1.