A Far Ultraviolet Spectroscopic Analysis of BZ Ursae Majoris

TL;DR

This study analyzes HST ultraviolet spectra of the dwarf nova BZ UMa during quiescence, revealing a white dwarf atmosphere at 15,000K and emphasizing the importance of hydrogen satellite lines in spectral modeling.

Contribution

It provides the first detailed spectral analysis of BZ UMa's white dwarf atmosphere, incorporating hydrogen satellite lines for accurate modeling.

Findings

White dwarf temperature estimated at 15,000K

Distance to BZ UMa is about 156 parsecs

Hydrogen satellite lines significantly affect the spectrum

Abstract

We present an analysis of the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) far ultraviolet snapshot spectrum of the dwarf nova BZ UMa taken during quiescence. We find that the flux continuum is consistent with that of a white dwarf atmosphere with a temperature of 15,000K, and a distance of about 156pc when assuming a white dwarf gravity of log(g)=7.5. We also show that the hydrogen quasi-molecular satellite lines opacity affects the spectrum around 1300-1400 A and has to be included to fine-tune the spectral modeling, this is self-consistent with the low stellar temperature we find.