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

Walborn, Nolan R.; Morrell, Nidia I.; Naze, Yael; Wade, Gregg A.; Bagnulo, Stefano; Barba, Rodolfo H.; Maiz Apellaniz, Jesus; Howarth, Ian D.; Evans, Christopher J.; Sota, Alfredo
The Astronomical Journal, Volume 150, Issue 4, article id. 99, 7 pp. (2015).


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.