Time dependence of the UV resonance lines in the cataclysmic variables SU UMa, RX And and 0623+71.

Abstract

IUE observations of the dwarf novae SU UMa and RX And, and of the nova-like variable 0623 + 71 are presented. At the time of observation, SU UMa and RX And were in outburst. All three systems show variability in the wind-formed UV resonance lines of N V 1240 A, Si IV 1397 A and C IV 1549 A on timescales of hours. The amplitude of variation is smallest in RX And and largest in 0623 + 71. There is evidence that the variations observed in SU UMa's UV spectrum repeat on the orbital period. The observations of SU UMa also reveal variability in the continuum flux during the decline from outburst maximum that is much more marked in the UV than at optical wavelengths. This and the line profile variations are discussed briefly.