Hubble Space Telescope STIS Spectroscopy of Nova T Aurigae 1891

Abstract

T Aurigae is an eclipsing old nova that 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 of the order of 10−8 M ⊙ yr−1, for a white-dwarf mass of M wd ≈ 0.7 ± 0.2M ⊙, an inclination of i ∼ 60°, and a Gaia distance of of 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 Lyα absorption feature is attributed to a large interstellar-medium hydrogen-column density of the order of 1021cm−2 toward T Aur, as corroborated by the value of its reddening E(B − V) = 0.42 ± 0.08.