Time-resolved ultraviolet spectroscopy of the cataclysmic variable, PG 1711 + 336

Abstract

Low-resolution IUE ultraviolet observations of the cataclysmic variable, PG 1711 + 336, are presented. The spectra reveal extensive variability in the windformed C IVλ1550 resonance line P Cygni profiles, on time-scales as short as ~ hours. We demonstrate that the high-resolution IUE spectrum of the nova-like system V3885 Sgr, convolved with the IUE low-resolution instrumental profile, provides a good match to the low-resolution wind lines of PG 1711 + 336 at some epochs. Hot-star wind theory and spherical symmetry are assumed in order to model the high-resolution data. The results yield a crude time-independent (lower-limit) estimate for the product of mass-loss rate and ion fraction. Moments of the observed P Cygni profiles in PG 1711 + 336 are measured to quantify the wind variability, and suggest that the C IV wind column densities may vary by a factor of ~ 2 in ~ 1 hour. We estimate changes of a factor of ~ 2 in the edge velocities of the shortward-shifted resonance lines, with maximum values of |$\sim 4500\enspace \rm km\enspace s^{-1}$|⁠. The stellar-wind variability is not accompanied by any significant changes in the continuum flux level or distribution over |$\sim 1150-3200$| Å. The mean UV continuum may be fitted by a power law of the form |${f}_{\lambda }\propto{\lambda}^{\sim(-2.0\pm0.1)}$|⁠. These limited data do not suggest a simple correlation between the wind variability and the orbital phase of PG 1711 + 336.