[en] The Of?p star CPD -28°2561 was monitored at high energies with XMM-Newton and HST. In X-rays, this magnetic oblique rotator displays bright and hard emission that varies by ~55 per cent with rotational phase. These changes occur in phase with optical variations, as expected for magnetically confined winds; there are two maxima and two minima in X-rays during the 73 d rotational period of CPD -28°2561. However, contrary to previously studied cases, no significant hardness variation is detected between minima and maxima, with the exception of the second minimum which is slightly distinct from the first one. In the UV domain, broad-band fluxes remain stable while line profiles display large variations. Stronger absorptions at low velocities are observed when the magnetic equator is seen edge-on, which can be reproduced by a detailed 3D model. However, a difference in absorption at high velocities in the C IV and N V lines is also detected for the two phases where the confined wind is seen nearly pole-on. This suggests the presence of strong asymmetries about the magnetic equator, mostly in the free-flowing wind (rather than in the confined dynamical magnetosphere).
Research Center/Unit :
LiSRI - Liège Space Research Institute - ULiège
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Nazé, Yaël ; Université de Liège > Groupe d'astrophysique des hautes énergies (GAPHE)
Sundqvist, Jon O.; Bartol Research Institute, University of Delaware, Newark, DE 19716, USA ; Institut für Astronomie und Astrophysik der Universität München, Scheinerstr. 1, D-81679 München, Germany
Fullerton, Alex W.; Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
ud-Doula, Asif; Penn State Worthington Scranton, Dunmore, PA 18512, USA
Wade, Gregg A.; Department of Physics, Royal Military College of Canada, PO Box 17000, Station Forces, Kingston, ON K7K 4B4, Canada
Rauw, Grégor ; Université de Liège > Groupe d'astrophysique des hautes énergies (GAPHE)
Walborn, Nolan R.; Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA)
Language :
English
Title :
The changing UV and X-ray properties of the Of?p star CPD -28°2561
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