Spectral mapping of the accretion flow of UU Aquarii

Abstract

Time-resolved spectroscopy of the novalike variable UU Aquarii is analyzed with eclipse mapping techniques to produce spatially resolved spectra of its accretion disc and gas stream as a function of distance from disc centre in the range 3600-7000 Å. The spectrum of inner disc shows a blue continuum filled with deep, narrow absorption lines which transition to emission with clear P Cygni profiles at intermediate and large radii. The spectrum of the uneclipsed component has strong HI and HeI emission lines and Balmer jump in emission and is explained as optically thin emission from a vertically extended disc wind. Most of the line emission probably arises from the wind. The spatially-resolved spectra also suggest the existence of gas stream penetration in UU Aqr, which can be seen down to $R \simeq 0.2 R_{L1}$.