Red noise and pulsations in evolved massive stars

Abstract

ABSTRACT We examine high-cadence space photometry taken by the Transiting Exoplanet Survey Satellite (TESS) of a sample of evolved massive stars: 26 Wolf–Rayet stars (WRs) and eight luminous blue variables (LBVs) or candidate LBVs. To avoid confusion problems, only stars without bright Gaia neighbours and without evidence of bound companions are considered. This leads to a clean sample, the variability properties of which should truly reflect the properties of the WR and LBV classes. Red noise is detected in all cases and its fitting reveals characteristics very similar to those found for OB stars. Coherent variability is also detected for 20 per cent of the WR sample. Most detections occur at moderately high frequency (3–14 d−1), hence they are most probably linked to pulsational activity. This work doubles the number of WRs known to exhibit high-frequency signals.