The Amazing Old Nova Q Cygni: A Far Ultraviolet Synthetic Spectral Analysis

TL;DR

This study analyzes the far ultraviolet spectrum of Q Cygni, an old nova, revealing that its FUV flux is dominated by a luminous accretion disk with a specific accretion rate, and estimates its distance at approximately 741 parsecs.

Contribution

First synthetic spectral analysis of Q Cygni's FUV spectrum using accretion disk and white dwarf models, providing insights into its accretion rate and distance.

Findings

Accretion disk dominates the FUV flux of Q Cygni.

Estimated accretion rate of 2-3 x 10^{-9} Msun/yr.

Distance to Q Cygni is approximately 741 parsecs.

Abstract

Q Cygni (Nova Cygni 1876) is the third oldest old novae (after WY Sge and V841 Oph) with a long orbital period of 10.08 hours and spectroscopic peculiarities in the optical including the presence of variable wind outflow revealed by optical P Cygni profiles in the HeI lines and H alpha beta (Kafka et al. 2003). We have carried out a synthetic spectral analysis of a far ultraviolet IUE archival spectrum of Q Cygni using our optically thick, steady state, accretion disk models and model white dwarf photospheres. We find that the accretion light of a luminous accretion disk dominates the FUV flux of the hot component with a rate of accretion 2-3 1.E-9 Msun/yr. We find that Q Cygni lies at a distance of 741 \pm 110 pc . The implications of our results for theoretical predictions for old novae are presented.