Extreme resonance line profile variations in the ultraviolet spectra of NGC 1624-2: probing the giant magnetosphere of the most strongly magnetized known O-type star Article Swipe
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· 2018
· Open Access
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· DOI: https://doi.org/10.1093/mnras/sty3227
· OA: W2900790158
In this paper, we present high-resolution HST/COS observations of the extreme\nmagnetic O star NGC 1624-2. These represent the first ultraviolet spectra of\nthis archetypal object. We examine the variability of its wind-sensitive\nresonance lines, comparing it to that of other known magnetic O stars. In\nparticular, the observed variations in the profiles of the CIV and SiIV\ndoublets between low state and high state are the largest observed in any\nmagnetic O-type star, consistent with the expected properties of NGC 1624-2's\nmagnetosphere. We also observe a redshifted absorption component in the low\nstate, a feature not seen in most stars. We present preliminary modelling\nefforts based on the Analytic Dynamical Magnetosphere (ADM) formalism,\ndemonstrating the necessity of using non-spherically symmetric models to\ndetermine wind/magnetospheric properties of magnetic O stars.\n
