Eclipse Mapping of the Accretion Disk Wind in the Cataclysmic Variable UX Ursae Majoris

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Abstract
We present the results of an effort to model recent HST eclipse observations of the C IV 1550 Å resonance line in the high-inclination nova-like cataclysmic variable UX UMa. Assuming this line to be predominantly wind-formed, we are able to roughly reproduce the shapes and strengths of the observed line profiles (both away from and during eclipse) within the framework of a simple kinematic model in which the outflow is described as a rotating, biconical accretion disk wind. Our preferred model also matches most of the detailed behavior of different parts of the C IV line profile (blue wing, line center, and red wing) as a function of orbital phase. The most important result of our modeling is that it strongly suggests the presence of a high column (NH ~ 1023 cm-2), relatively dense (ne 4 × 1012 cm-3), and only slowly outflowing (vpoloidal vescape) transition region between the disk photosphere and the fast-moving wind. We also find that the outflow from UX UMa is probably only moderately collimated (the outer opening angle of our preferred model is θmax 65°). Finally, the rotational disturbance seen in the data is fitted reasonably well by our model, in which the rotational component of motion in the wind is fixed by conserving the specific angular momentum of the outflowing material. The implications of these results for dynamical models of disk-driven winds are discussed.