Hubble Space Telescope STIS Spectroscopy of Nova T Aurigae 1891

TL;DR

This study uses HST/STIS ultraviolet spectroscopy and Gaia distance measurements to model the accretion disk of the old nova T Aurigae, revealing details about its mass transfer rate, disk structure, and interstellar medium absorption.

Contribution

It provides the first detailed spectral modeling of T Aurigae's accretion disk using precise Gaia distance data, offering new insights into its physical parameters and circumstellar environment.

Findings

Accretion disk mass transfer rate ~10^{-8} M_sun/yr

White dwarf mass estimated at ~0.7 M_sun

Interstellar hydrogen column density ~10^{21} cm^{-2}

Abstract

T Aurigae is an eclipsing old nova which exploded in 1891. At a Gaia EDR3 distance of 815-871 pc, it is a relatively nearby old nova. Through ultraviolet spectral modeling and using the new precise Gaia distance, we find that the HST/STIS spectrum of T Aurigae is consistent with an accretion disk with a mass transfer rate $\dot{M}$ of the order of $10^{-8}M_{\odot}$/yr, for a white dwarf mass of $M_{\rm wd} \approx 0.7 \pm 0.2 M_{\odot}$, an inclination of $i \sim 60^{\circ}$, and a Gaia distance of of $840_{-25}^{+31}$~pc. The sharp absorption lines of metals cannot form in the disk and are likely forming in material above the disk (e.g. due stream disk overflow), in circumbinary material, and/or in material associated with the ejected shell from the 1891 nova explosion. The saturated hydrogen Ly$\alpha$ absorption feature is attributed to a large interstellar medium hydrogen column density of the order of $10^{21}$cm$^{-2}$ towards T Aur, as corroborated by the value of its reddening $E(B-V)=0.42 \pm 0.08$.