Spectral Variations of Of?p Oblique Magnetic Rotator Candidates in the Magellanic Clouds

TL;DR

This study presents optical spectroscopic monitoring of Of?p stars in the Magellanic Clouds, confirming their magnetic nature through spectral variations and linking these to photometric rotational periods, thus supporting their classification as oblique magnetic rotators.

Contribution

It provides the first systematic spectral variation analysis of Magellanic Cloud Of?p stars, strengthening their magnetic candidacy and linking spectral changes to rotational periods.

Findings

Spectral variations consistent with Of?p class in Magellanic Clouds

Photometric data supports rotational period determination

Spectral variations linked to magnetic oblique rotator model

Abstract

Optical spectroscopic monitoring has been conducted of two O stars in the Small and one in the Large Magellanic Cloud, the spectral characteristics of which place them in the Of?p category, which has been established in the Galaxy to consist of oblique magnetic rotators. All of these Magellanic stars show systematic spectral variations typical of the Of?p class, further strengthening their magnetic candidacy to the point of virtual certainty. The spectral variations are related to photometric variations derived from OGLE data by Naze et al. (2015) in a parallel study, which yields rotational periods for two of them. Now circular spectropolarimetry is required to measure their fields, and ultraviolet spectroscopy to further characterize their low-metallicity, magnetically confined winds, in support of hydrodynamical analyses.