Nolan R. Walborn, Nidia I. Morrell, Yaël Nazé, Gregg A. Wade, Stefano Bagnulo, Rodolfo H. Barbá, Jesús Maíz Apellániz, Ian D. Howarth, Christopher J. Evans, Alfredo Sota

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

Figure 4. Phase plot of the He II λ4686 and Hβ emission-line EWs in 2dFS 936, compared with its lightcurve from Nazé et al. (2015).

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 sys- tematic 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 Nazé 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.

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Last Revised: 2015 July 27th