The Highly Variable Wind from WD J005311, the Stellar Remnant of the Peculiar Galactic Supernova of 1181

TL;DR

WD J005311, a stellar remnant of a 1181 supernova, exhibits complex emission line variability and potential rotation and disk instabilities, revealing insights into its wind and magnetosphere dynamics.

Contribution

This study provides the first detailed time-resolved spectroscopy of WD J005311, uncovering emission line variability and linking it to wind instabilities and magnetospheric disk behavior.

Findings

Emission lines show variability on multiple time-scales.

Broad LPVs suggest wind instabilities similar to Wolf-Rayet stars.

Detection of a possible rotation period of about two hours.

Abstract

WD J005311 is the peculiar stellar remnant of the Galactic supernova from 1181, and appears to have been the merger of two white dwarfs. We present time-resolved spectroscopy of WD J005311 showing emission line variability on a wide range of time-scales. The strong O VI emission feature displays line profile variations (LPVs) on two distinct velocity scales. Broad variations with amplitudes of $\pm$10% of the line flux are seen over the entire O VI line. These broad LPVs likely arise from instabilities in the line-driven wind produced in many Wolf-Rayet stars. There is a hint of coherent structure in the broad LPVs that is consistent with rotation over roughly two hours, although the features survive for less than a full cycle. Low-amplitude, narrow LPVs are also detected within the central $\pm$5000 km/s of the O VI line. We associate these features with an unstable disk formed from the rigidly rotating magnetosphere (RRM) of the remnant white dwarf. We also analyze archival near-ultraviolet photometry of WD J005311 and find a pseudo-periodic oscillation with an hour-long time-scale that maybe associated with the breakout instability of the RRM disk.