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
David-Uraz, A.; Erba, C.; Petit, V.et al.
2019 • In Monthly Notices of the Royal Astronomical Society, 483, p. 2814-2824
stars: early-type; stars: individual: NGC 1624-2; stars: magnetic field; stars: winds; outflows; ultraviolet: stars
Abstract :
[en] In this paper, we present high-resolution HST/COS observations of the extreme magnetic O star NGC 1624-2. These represent the first ultraviolet spectra of this archetypal object. We examine the variability of its wind-sensitive resonance lines, comparing it to that of other known magnetic O stars. In particular, the observed variations in the profiles of the C IV and Si IV doublets between low state and high state are the largest observed in any magnetic O-type star, consistent with the expected properties of NGC 1624-2's magnetosphere. We also observe a redshifted absorption component in the low state, a feature not seen in most stars. We present preliminary modelling efforts based on the Analytic Dynamical Magnetosphere (ADM) formalism, demonstrating the necessity of using non-spherically symmetric models to determine wind/magnetospheric properties of magnetic O stars.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
David-Uraz, A. ; Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
Erba, C.; Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
Petit, V.; Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
Fullerton, A. W.; Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
Martins, F.; LUPM-UMR 5299, CNRS & Université Montpellier, Place Eugene Bataillon, F-34095 Montpellier Cedex 05, France
Walborn, N. R.; Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
MacInnis, R.; Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
Barbá, R. H. ; Departamento de Física y Astronomía, Universidad de La Serena, Av. Cisternas 1200 Norte, La Serena, Chile
Cohen, D. H.; Department of Physics and Astronomy, Swarthmore College, Swarthmore, PA 19081, USA
Maíz Apellániz, J. ; Centro de Astrobiología, CSIC-INTA. Campus ESAC, Camino bajo del castillo s/n, E-28 692 Villanueva de la Cañada. Spain
Nazé, Yaël ; Université de Liège - ULiège > Groupe d'astrophysique des hautes énergies (GAPHE)
Owocki, S. P.; Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
Sundqvist, J. O.; Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium
ud-Doula, A.; Penn State Scranton, 120 Ridge View Drive, Dunmore, PA 18512, USA
Wade, G. A.; Department of Physics and Space Science, Royal Military College of Canada, PO Box 17000, Stn Forces, Kingston, ON K7K 7B4, Canada)
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
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