TY  - JOUR
A1  - Kholtygin, A. F.
A1  - Fabrika, S. N.
A1  - Rusomarov, N.
A1  - Hamann, Wolf-Rainer
A1  - Kudryavtsev, D. O.
A1  - Oskinova, Lida
A1  - Chountonov, G. A.
T1  - Line profile variability and magnetic fields of Wolf-Rayet stars: WR 135
 and WR 136
JF  - ASTRONOMISCHE NACHRICHTEN
N2  - We have obtained spectropolarimetric observations of two Wolf-Rayet stars, WR 135 (WC8) and WR 136 (WN6), with the 6-m Russian telescope in July 2009 and July 2010. We have studied the He II 5412 angstrom line region, which contains also the C IV 5469 angstrom line (for WR 135 only). Our goals were to investigate the rapid line-profile variability (LPV) in WR star spectra and to search for magnetic fields. We find small amplitude emission peaks moving from the center of He II line to its wings during the night in spectra of both stars. These emission peaks are likely a signature of accelerating clumps in the stellar wind. We obtained upper limits of the magnetic field strength: approximate to 200G for WR 135 and approximate to 50G for WR 136. (C) 2011 WILEY-VCH Verlag GmbH&Co. KGaA, Weinheim
KW  - stars: atmospheres
KW  - stars: magnetic fields
KW  - stars: winds
KW  - stars: Wolf-Rayet
KW  - techniques: polarimetric
Y1  - 2011
U6  - https://doi.org/10.1002/asna.201111595
SN  - 0004-6337
VL  - 332
IS  - 9-10
SP  - 1008
EP  - 1011
PB  - WILEY-BLACKWELL
CY  - MALDEN
ER  - 
TY  - JOUR
A1  - Oskinova, Lida
A1  - Hamann, Wolf-Rainer
A1  - Cassinelli, Joseph P.
A1  - Brown, John C.
A1  - Todt, Helge Tobias
T1  - X-ray emission from massive stars with magnetic fields
JF  - Astronomische Nachrichten = Astronomical notes
N2  - We investigate the connections between the magnetic fields and the X-ray emission from massive stars. Our study shows that the X-ray properties of known strongly magnetic stars are diverse: while some comply to the predictions of the magnetically confined wind model, others do not. We conclude that strong, hard, and variable X-ray emission may be a sufficient attribute of magnetic massive stars, but it is not a necessary one. We address the general properties of X-ray emission from "normal" massive stars, especially the long standing mystery about the correlations between the parameters of X-ray emission and fundamental stellar properties. The recent development in stellar structure modeling shows that small-scale surface magnetic fields may be common. We suggest a "hybrid" scenario which could explain the X-ray emission from massive stars by a combination of magnetic mechanisms on the surface and shocks in the stellar wind. The magnetic mechanisms and the wind shocks are triggered by convective motions in sub-photospheric layers. This scenario opens the door for a natural explanation of the well established correlation between bolometric and X-ray luminosities.
KW  - stars: magnetic fields
KW  - stars: mass-loss
KW  - stars: winds, outflows
KW  - stars: Wolf-Rayet
KW  - techniques: spectroscopic
KW  - X-rays: stars
Y1  - 2011
U6  - https://doi.org/10.1002/asna.201111602
SN  - 0004-6337
VL  - 332
IS  - 9-10
SP  - 988
EP  - 993
PB  - Wiley-Blackwell
CY  - Malden
ER  -