Photometric identification of the periods of the first candidate extragalactic magnetic massive stars

TL;DR

This study investigates the photometric variability of five candidate extragalactic magnetic massive stars in the Magellanic Clouds, revealing significant variability and periodicity that support their classification as strongly magnetized O stars, similar to Galactic Of?p stars.

Contribution

First detailed photometric analysis of candidate extragalactic magnetic massive stars, providing evidence of their magnetic nature and periodic variability.

Findings

All studied stars show significant variability.

Three stars exhibit clear periodic variations.

Photometric and spectral data support their classification as magnetized O stars.

Abstract

Galactic stars belonging to the Of?p category are all strongly magnetic objects exhibiting rotationally modulated spectral and photometric changes on timescales of weeks to years. Five candidate Of?p stars in the Magellanic Clouds have been discovered, notably in the context of ongoing surveys of their massive star populations. Here we describe an investigation of their photometric behaviour, revealing significant variability in all studied objects on timescales of one week to more than four years, including clearly periodic variations for three of them. Their spectral characteristics along with these photometric changes provide further support for the hypothesis that these are strongly magnetized O stars, analogous to the Of?p stars in the Galaxy.