1999A&A...347..178G

We present optical and ultraviolet spectroscopy of TT Ari obtained during the 1982-85 low state. In November/December 1983, accretion had almost completely ceased, unveiling both the white dwarf and the secondary star. The IUE spectrum obtained during that occasion contains absorption lines of Lyα, SiIV, CIV, and HeII. We derive a photospheric temperature of T_wd=39000K and find the abundances of Carbon and Helium to be 0.5 and 2.0 times solar, respectively. An upper limit of vsini≲750km/s is derived from the metal line profiles. Comparison with the IUE spectrum taken one year earlier during the low state shows no evidence for cooling of the white dwarf over a time span of one year. The optical spectrum displays Balmer absorption lines from the white dwarf, overlayed with narrow emission lines, as well as the TiO absorption bands of the secondary star, for which we derive a spectral type M3.5±0.5. A distance of d=335±50pc is derived from both, the white dwarf and the secondary star. The data indicate that the low-state accretion disc in TT Ari was optically thin at least for r≲12R_wd.