No detection of Strange Mode Pulsations in massive prime candidate

TL;DR

This study conducted high-precision infrared photometry on the hottest Wolf-Rayet star WR 2 to detect predicted strange mode pulsations but found no significant variability, challenging existing theoretical expectations.

Contribution

The paper provides the first high-precision photometric search for SMPs in WR 2, setting upper limits that contradict current theoretical predictions.

Findings

No periodic variations above 2.5 mmag detected

SMP amplitudes are at least an order of magnitude smaller than predicted

Results challenge existing models of SMPs in massive stars

Abstract

The most violent strange mode pulsations (SMPs) are expected in classical WR stars, the bare, compact helium-burning cores of evolved massive stars, where SMPs are predicted to manifest themselves in cyclic photometric variability with periods ranging from minutes to hours and amplitudes in the several to tens of mmag range. Since WR\,2 is one of the hottest WR stars known, it should make it an excellent candidate for SMPs. However, our high-precision near infrared photometric campaign shows no periodic variations with an amplitude higher than 2.5 mmag on a timescale of ~6 hours, which is more than an order of magnitude smaller than the theoretical predictions.