Evidence for eccentric, precessing gaseous debris in the circumstellar absorption towards WD 1145+017

TL;DR

This study presents time-series spectra of WD 1145+017 showing dramatic velocity reversals in circumstellar absorption over 2.2 years, consistent with eccentric, precessing gas rings undergoing general relativistic precession.

Contribution

It provides the first evidence of eccentric, precessing gaseous debris rings around a white dwarf, advancing understanding of circumstellar disk dynamics.

Findings

Complete velocity reversals observed over 2.2 years

Absorption depth increased by a factor of two

Precession model predicts future line profile changes

Abstract

We present time-series spectra revealing changes in the circumstellar line profiles for the white dwarf WD 1145+017. Over the course of 2.2 years, the spectra show complete velocity reversals in the circumstellar absorption, moving from strongly red-shifted in 2015 April to strongly blue-shifted in 2017 June. The depth of the absorption also varies, increasing by a factor of two over the same period. The dramatic changes in the line profiles are consistent with eccentric circumstellar gas rings undergoing general relativistic precession. As the argument of periapsis of the rings change relative to the line of sight, the transiting gas shifts from receding in 2016 to approaching in 2017. Based on the precession timescales in the favored model, we make predictions for the line profiles over the next few years. Spectroscopic monitoring of WD 1145+017 will test these projections and aid in developing more accurate white dwarf accretion disk models.