A Far-Ultraviolet Study of the Old Nova V841 Ophiuchi

Abstract

We have carried out a synthetic spectral analysis of archival International Ultraviolet Explorer spectra of the old nova V841 Oph (Nova Oph 1848) taken 15 years apart. The spectra reveal a rising continuum shortward of 1560 Å, a C IV P Cygni profile indicative of wind outflow associated with disk accretion in one spectrum, a deep Lyα profile, and strong N V (1238 Å, 1242 Å) and O V (1371 Å) wind/coronal absorption lines. Numerous sharp interstellar resonance lines are also present. A grid of high-gravity atmospheres and accretion disk models spanning a wide range of inclinations, accretion rates, and white dwarf masses was compared to the dereddened spectra. We find that for a steady-state accretion disk model to account for the FUV spectra, the accretion rate is only ~3×10^-11 M_solar yr^-1, 147 yr after its outburst in 1848, with an implied distance within ~300 pc. The accretion rate at 147 yr postoutburst is smaller than expected for an old nova.