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Magnetic Field Measurements Of O Stars With Fors 1 At The Vlt., S. Hubrig, M. Schöller, R. S. Schnerr, J. F. González, R. Ignace, H. F. Henrichs
Magnetic Field Measurements Of O Stars With Fors 1 At The Vlt., S. Hubrig, M. Schöller, R. S. Schnerr, J. F. González, R. Ignace, H. F. Henrichs
Richard Ignace
Context.The presence of magnetic fields in O-type stars has been suspected for a long time. The discovery of these fields would explain a wide range of well documented enigmatic phenomena in massive stars, in particular cyclical wind variability, Hα emission variations, chemical peculiarity, narrow X-ray emission lines, and non-thermal radio/X-ray emission.
Aims.To investigate the incidence of magnetic fields in O stars, we acquired 38 new spectropolarimetric observations with FORS 1 (FOcal Reducer low dispersion Spectrograph) mounted on the 8-m Kueyen telescope of the VLT.
Methods.Spectropolarimetric observations were obtained at different phases for a sample of 13 O …
The Effects Of Clumps In Explaining X-Ray Emission Lines From Hot Stars., J. P. Cassinelli, R. Ignace, W. L. Waldron, J. Cho, N. A. Murphy, A. Lazarian
The Effects Of Clumps In Explaining X-Ray Emission Lines From Hot Stars., J. P. Cassinelli, R. Ignace, W. L. Waldron, J. Cho, N. A. Murphy, A. Lazarian
Richard Ignace
It is now well established that stellar winds of hot stars are fragmentary and that the X-ray emission from stellar winds has a strong contribution from shocks in winds. Chandra high spectral resolution observations of line profiles of O and B stars have shown numerous properties that had not been expected. Here we suggest explanations by considering the X-rays as arising from bow shocks that occur where the stellar wind impacts on spherical clumps in the winds. We use an accurate and stable numerical hydrodynamic code to obtain steady state physical conditions for the temperature and density structure in a …
Phase-Dependent X-Ray Observations Of The Beta Lyrae System: No Eclipse In The Soft Band., R. Ignace, L. M. Oskinova, W. L. Waldron, J. L. Hoffman, W.-R. Hamann
Phase-Dependent X-Ray Observations Of The Beta Lyrae System: No Eclipse In The Soft Band., R. Ignace, L. M. Oskinova, W. L. Waldron, J. L. Hoffman, W.-R. Hamann
Richard Ignace
Aims.We report on observations of the eclipsing and interacting binary beta Lyrae from the Suzaku X-ray telescope. This system involves an early B star embedded in an optically and geometrically thick disk that is siphoning atmospheric gases from a less massive late B II companion.
Methods.Motivated by an unpublished X-ray spectrum from the Einstein X-ray telescope suggesting unusually hard emission, we obtained time with Suzaku for pointings at three different phases within a single orbit.
Results.From the XIS detectors, the softer X-ray emission appears typical of an early-type star. What is surprising is the remarkably unchanging character …