Spectroscopy of the double-lined dwarf nova AT Ara

Optical spectroscopy of the dwarf nova U Geminorum

The dwarf nova U Gem is unique in having a direct measurement of the K-velocity of its white dwarf from HST spectra (K 1 = 107 ± 2 km s −1 , Long et al. 1999). We present high-resolution optical spectra of the dwarf nova U Gem in quiescence taken to test the accuracy to which the HST value can be recovered from optical data. We find that, even with data of very high signal-to-noise ratio on thi...

Telescope Far Ultraviolet Spectroscopy of the Dwarf Nova

We obtained three consecutive HST spectroscopic observations of a single superoutburst of the dwarf nova VW Hydri. The spectra cover the beginning, middle, and end of the superoutburst. All of the spectra are dominated by strong absorption lines due to CIII (1175 Å), Lyman alpha (1216 Å), NIV (1238 Å, 1242 Å), SII (1260-65 Å), SIII (1300 Å), CII (1335 Å), SIV (1394 Å, 1402 Å) and CIV (1548 Å, 1...

A double-frequency dwarf nova oscillation in OY Car

We have detected coherent oscillations (“dwarf nova oscillations”) in Hubble Space Telescope spectra of the dwarf nova OY Car. The oscillations were seen towards the end of a superoutburst of OY Car. The oscillations are extraordinary compared to the many other examples in the literature for two reasons. First, their amplitude is large, with a peak-to-peak variation of 8 to 20% of the total flu...

The Dwarf Nova Pq Andromedae

The Nature of Dwarf Nova Outbursts

We show that if the dwarf-nova disc instability model includes the effects of heating by stream impact and tidal torque dissipation in the outer disc, the calculated properties of dwarf-nova outbursts change considerably, and several notorious deficiencies of this model are repaired. In particular: (1) outside-in outbursts occur for mass transfer rates lower than in the standard model as requir...