Far Ultraviolet Spectroscopy of Old Novae I. V603 Aquila

TL;DR

This study analyzes far ultraviolet spectra of the old nova V603 Aql using synthetic spectral modeling to determine its accretion rate and other properties, providing insights into its post-outburst state.

Contribution

First detailed synthetic spectral analysis of V603 Aql using multiple UV observations with updated distance and white dwarf parameters.

Findings

Mass transfer rate of 1.5-2.2 x 10^-9 solar masses per year

Consistent results across FUSE and HST spectra

Accretion rate varies with white dwarf mass

Abstract

We present the results of a synthetic spectral analysis of the far ultraviolet archival IUE, HST and FUSE observations of the fast old nova V603 Aql, obtained some 90 years after its 1918 nova outburst. Our analysis utilizes the new Hubble FGS parallax distance for this nearly face-on old nova, a high white dwarf mass and a low reddening. Our analysis includes non-truncated optically thick accretion disks since V603 Aql is neither a polar nor an intermediate polar. Our synthetic spectral modeling of the FUSE and HST spectra analyzed separately indicate a mass transfer rate of 1.5-2.2xe-9 solar mass per year for the FUSE and HST spectra respectively, assuming a WD mass of 1.2Msun. The mass accretion rate also depends on the assumed WD mass, and increases by a factor of two for a WD mass of 0.8Msun. Combining the FUSE and HST spectra together lead to the same results. Potential implications are discussed.