TY - JOUR
T1 - Magnetic field measurements of O stars with FORS 1 at the VLT.
AU - Hubrig, S.
AU - Schöller, M.
AU - Schnerr, R. S.
AU - González, J. F.
AU - Ignace, Richard
AU - Henrichs, H. F.
N1 - S. Hubrig, M. Schöller, R. S. Schnerr, J. F. González, R. Ignace, and H. F. Henrichs. "Magnetic field measurements of O stars with FORS 1 at the VLT." Astronomy & Astrophysics 490.2 (2008): 793-800.
DOI: 10.1051/0004-6361:200810171
Available at: http://works.bepress.com/richard_ignace/16
PY - 2008/11
Y1 - 2008/11
N2 - 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 stars. Ten stars were observed in the spectral range 348−589 nm, HD 36879 and HD 148937 were observed in the spectral region 325−621 nm, and HD 155806 was observed in both settings. To prove the feasibility of the FORS 1 spectropolarimetric mode for the measurements of magnetic fields in hot stars, we present in addition 12 FORS 1 observations of the mean longitudinal magnetic field in θ1 Ori C and compare them with measurements obtained with the MuSiCoS, ESPaDOnS, and Narval spectropolarimeters. Results. Most stars in our sample, which were observed on different nights, show a change of the magnetic field polarity, but a field at a significance level of 3σ was detected in only four stars, HD 36879, HD 148937, HD 152408, and HD 164794. The largest longitudinal magnetic field, Bz = −276 ± 88 G, was detected in the Of?p star HD 148937. We conclude that large-scale organized magnetic fields with polar field strengths larger than 1 kG are not widespread among O-type stars.
AB - 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 stars. Ten stars were observed in the spectral range 348−589 nm, HD 36879 and HD 148937 were observed in the spectral region 325−621 nm, and HD 155806 was observed in both settings. To prove the feasibility of the FORS 1 spectropolarimetric mode for the measurements of magnetic fields in hot stars, we present in addition 12 FORS 1 observations of the mean longitudinal magnetic field in θ1 Ori C and compare them with measurements obtained with the MuSiCoS, ESPaDOnS, and Narval spectropolarimeters. Results. Most stars in our sample, which were observed on different nights, show a change of the magnetic field polarity, but a field at a significance level of 3σ was detected in only four stars, HD 36879, HD 148937, HD 152408, and HD 164794. The largest longitudinal magnetic field, Bz = −276 ± 88 G, was detected in the Of?p star HD 148937. We conclude that large-scale organized magnetic fields with polar field strengths larger than 1 kG are not widespread among O-type stars.
KW - FORS 1
KW - Magnetic field measurements
KW - O stars
KW - VLT
U2 - 10.1051/0004-6361:200810171
DO - 10.1051/0004-6361:200810171
M3 - Article
VL - 490
JO - Astronomy & Astrophysics
JF - Astronomy & Astrophysics
ER -