Detection of the secondary star in HT Cassiopeiae

Low-resolution spectra of the eclipsing dwarf nova HT Cas, taken over the range 5000-9800 A show TiO bands and Na I absorption lines from the secondary star. From the TiO band ratio at mid-eclipse it is estimated that the secondary star contributes about 37 percent of the light at 7500 A during the eclipse, and that it has a Boeshaar spectral type M5.4 + or - 0.3. The mass, radius, and luminosity of the secondary star are all consistent with main-sequence values. The TiO band strength diminishes greatly near phase 0.5, but an eclipse by the disk is not sufficient to explain this. The radial velocity is measured from the Na line near 8200 A for most of the spectra and (after a correction for the asymmetric distribution of absorption over the secondary star) its radial velocity semiamplitude K2 = 430 + or - 25 km/sec.