Time-resolved optical spectroscopy of IR GEM in quiescence

Abstract

Spectroscopic observations of the dwarf nova IR Gem in the range 4000-7000 A, covering a whole orbital period, are presented. The dates of the observations (February 3-6, 1987) were at the end of the decline from an outburst and the beginning of quiescence. Evidence of phase related variations in H-alpha equivalent width is found, showing a maximum at phase 0.5. The mean quiescence spectra are compared with published accretion disk models, deriving a mass transfer rate for the system of about 10 to the -10th solar mass/yr, but it is shown that these models do not reproduce satisfactorily the observed spectra. 13 refs.