1996A&A...311..889A

We present time resolved photometry and spectroscopy of the dwarf nova V485 Cen. Significant radial velocity variations are detected in Hα only for a period equal to the previously detected 59 min photometric period (Augusteijn et al., =1993A&A...267L..55A), and we conclude that this is the orbital period of the system. Hα shows two components which vary with this period. One component dominates the line wings and originates from a region centered on the white dwarf. The second component dominates the line center and originates in the hot spot (the so-called S-wave). Using various observational constraints we derive a mass ratio of q=M_WD/M_sec∼2.6 and a inclination of i∼20-30deg. Strong evidence is found for a significant contribution from the secondary to the spectrum at wavelengths longer than ∼5900Angstroems. We discuss the discovery of a 59min orbital period in the framework of evolutionary ideas about cataclysmic variables. The most likely explanation is that the secondary has a low, but finite, hydrogen content.