Rapid Variability in the Wind from the White Dwarf Merger Candidate J005311

The optical spectrum of the “zombie star” white dwarf merger candidate J005311 is similar to that of WO-type Wolf-Rayet (WR) stars; however the maximum expansion velocity for J005311 is more than three times faster than for WR stars at 16,000 km/s. The absolute magnitude and the extremely high surface temperature of the star suggests that this object is much more compact than a typical WR star, where the WR-like wind appears to be driven by a rapidly rotating, strong magnetic field. We observed J005311 with the twin Multi-Object Dual Spectrographs (MODS) at the Large Binocular Telescope (LBT) to search for emission line profile variations and derive statistical properties of its wind. Time-resolved spectra were obtained at three epochs in September and October of 2020 with the blue spectrographs out of synchronization to increase time resolution. We detect significant variability in the strong OVI 381.1/383.4 nm emission with amplitudes as high as 10% of the average flux. This variability likely corresponds to density fluctuations in the stellar outflow. Other variations in the emission profile are seen to change over a range of times-scales from days to minutes. Full widths of the coherent features are approximately 2000 km/s and appear to drift by as much as 8000 km/s over an hour.