HD188112: Supernova Ia progenitor?

TL;DR

This study uses UV spectra to constrain the mass of HD188112's unseen companion, suggesting it could be a supernova Ia progenitor, and measures its elemental abundances.

Contribution

It provides tighter constraints on the companion's mass and elemental abundances using UV spectral analysis, advancing understanding of this binary system.

Findings

Companion mass estimated between 1.05 and 1.25 solar masses.

Elemental abundances measured for magnesium, silicon, and iron.

Radial velocities agree with previous orbital predictions.

Abstract

HD188112 is an extremely low mass white dwarf in a close binary system. According to a previous study, the mass of HD188112 is $\sim$0.24 Msun and a lower limit of 0.73 Msun could be put for the mass of its unseen companion, a compact degenarate object. We used HST STIS spectra to measure the rotational broadening of UV metallic lines in HD188112, in order to put tighter constraints on the mass of its companion. By assuming that the system in is synchronous rotation, we derive a companion mass between 1.05 and 1.25 Msun. We also measure abundances for magnesium, silicon, and iron, respectively log $N$(X)/$N$(H) = $-$6.40, $-$7.25, and $-$5.81. The radial velocities measured from the UV spectra are found to be in very good agreement with the prediction based on the orbital parameters derived in the previous study made a decade ago.