TY  - JOUR
A1  - Schoeller, M.
A1  - Hubrig, Swetlana
A1  - Ilyin, Ilya
A1  - Kharchenko, N. V.
A1  - Briquet, Maryline
A1  - Gonzalez, J. F.
A1  - Langer, Norbert
A1  - Oskinova, Lida
T1  - Magnetic field studies of massive main sequence stars
JF  - Astronomische Nachrichten = Astronomical notes
N2  - We report on the status of our spectropolarimetric observations of massive stars. During the last years, we have discovered magnetic fields in many objects of the upper main sequence, including Be stars, beta Cephei and Slowly Pulsating B stars, and a dozen O stars. Since the effects of those magnetic fields have been found to be substantial by recent models, we are looking into their impact on stellar rotation, pulsation, stellar winds, and chemical abundances. Accurate studies of the age, environment, and kinematic characteristics of the magnetic stars are also promising to give us new insight into the origin of the magnetic fields. Furthermore, longer time series of magnetic field measurements allow us to observe the temporal variability of the magnetic field and to deduce the stellar rotation period and the magnetic field geometry. Studies of the magnetic field in massive stars are indispensable to understand the conditions controlling the presence of those fields and their implications on the stellar physical parameters and evolution.
KW  - stars: early-type
KW  - stars: magnetic fields
KW  - stars: kinematics
KW  - techniques: polarimetric
Y1  - 2011
U6  - https://doi.org/10.1002/asna.201111606
SN  - 0004-6337
VL  - 332
IS  - 9-10
SP  - 994
EP  - 997
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  -