Photometric White Dwarf Rotation

TL;DR

This study provides a comprehensive survey of white dwarf rotation periods using TESS data, revealing a median period of 3.9 hours for likely single WDs and highlighting discrepancies with asteroseismology results.

Contribution

It offers the first large-scale photometric rotation period census for white dwarfs and compares observational data with evolutionary models including angular momentum transfer mechanisms.

Findings

Median rotation period of 3.9 hours for likely single WDs

Distribution differs significantly from asteroseismology results

Models suggest low metallicity fits observed temperature-period relation

Abstract

We present a census of photometrically detected rotation periods for white dwarf (WD) stars. We analyzed the light curves of 9285 WD stars observed by the Transiting Exoplanet Survey Satellite up to Sector 69. Using Fourier transform analyses and the TESS_localize software, we detected variability periods for 318 WD stars. The 115 high-probability likely single WDs in our sample have a median rotational period of 3.9 hr and a median absolute deviation of 3.5 hr. Our distribution is significantly different from the distribution of the rotational period from asteroseismology, which exhibits a longer median period of 24.2 hr and a median absolute deviation of 12.1 hr. In addition, we reported nonpulsating periods for three known pulsating WDs with rotational periods previously determined by asteroseismology: NGC 1501, TIC 7675859, and G226-29. We also calculated evolutionary models including six angular momentum transfer mechanisms from the literature throughout evolution in an attempt to reproduce our findings. Our models indicate that the temperature-period relation of most observational data is best fitted by models with low metallicity, probably indicating problems with the computations of angular momentum loss during the high-mass-loss phase. Our models also generate internal magnetic fields through the Tayler-Spruit dynamo.