A Far Ultraviolet Study of the Old Nova V841 Oph

Abstract

We have carried out a synthetic spectral analysis of archival IUE spectra of the old nova V841 Oph (Nova Oph 1848) taken 15 years apart. The spectra reveal a rising continuum shortward of 1560Å, a C {\sc iv} P-Cygni profile indicative of wind outflow associated with disk accretion in one spectrum, a deep Ly $\alpha$ profile, and strong N {\sc v} (1238Å, 1242Å) and O {\sc v} (1371Å) 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 de-reddened spectra. We find that, for a steady state accretion disk model to account for the FUV spectra, the accretion rate is only $\sim$3 $\times$ 10${}^{-11}$ M$_{\sun}$/yr, 147 years after its outburst in 1848, with an implied distance within $\sim$300 pc. The accretion rate at 147 years post-outburst is smaller than expected for an old nova.

6 b/w figures, 2 tables, preprint accepted in the November 2005 issue of PASP