TY  - JOUR
A1  - Hubrig, Swetlana
A1  - Schöller, Markus
A1  - Kholtygin, Alexander F.
A1  - Tsumura, Hiroki
A1  - Hoshino, Akio
A1  - Kitamoto, Shunji
A1  - Oskinova, Lida
A1  - Ignace, Richard
A1  - Todt, Helge Tobias
A1  - Ilyin, Ilya
T1  - New multiwavelength observations of the Of?p star CPD-28 degrees 2561
JF  - Monthly notices of the Royal Astronomical Society
N2  - A rather strong mean longitudinal magnetic field of the order of a few hundred gauss was detected a few years ago in the Of?p star CPD -28 degrees 2561 using FORS2 (FOcal Reducer low dispersion Spectrograph 2) low-resolution spectropolarimetric observations. In this work, we present additional low-resolution spectropolarimetric observations obtained during several weeks in 2013 December using FORS 2 mounted at the 8-m Antu telescope of the Very Large Telescope (VLT). These observations cover a little less than half of the stellar rotation period of 73.41 d mentioned in the literature. The behaviour of the mean longitudinal magnetic field is consistent with the assumption of a single-wave variation during the stellar rotation cycle, indicating a dominant dipolar contribution to the magnetic field topology. The estimated polar strength of the surface dipole B-d is larger than 1.15 kG. Further, we compared the behaviour of the line profiles of various elements at different rotation phases associated with different magnetic field strengths. The strongest contribution of the emission component is observed at the phases when the magnetic field shows a negative or positive extremum. The comparison of the spectral behaviour of CPD -28 degrees 2561 with that of another Of?p star, HD 148937 of similar spectral type, reveals remarkable differences in the degree of variability between both stars. Finally, we present new X-ray observations obtained with the Suzaku X-ray Observatory. We report that the star is X-ray bright with log L-X/L-bol approximate to -5.7. The low-resolution X-ray spectra reveal the presence of a plasma heated up to 24 MK. We associate the 24 MK plasma in CPD -28 degrees 2561 with the presence of a kG strong magnetic field capable to confine stellar wind.
KW  - stars: atmospheres
KW  - stars: individual: CPD-28 degrees 2561
KW  - stars: magnetic field
KW  - stars: mass-loss
KW  - stars: variables: general
KW  - X-rays: stars
Y1  - 2015
U6  - https://doi.org/10.1093/mnras/stu2516
SN  - 0035-8711
SN  - 1365-2966
VL  - 447
IS  - 2
SP  - 1885
EP  - 1894
PB  - Oxford Univ. Press
CY  - Oxford
ER  -