On the incidence of magnetic fields in slowly pulsating B, β Cephei and B-type emission-line stars |
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| Authors: | J Silvester C Neiner H F Henrichs G A Wade V Petit E Alecian A-L Huat C Martayan J Power O Thizy |
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| Institution: | Department of Physics, Engineering Physics &Astronomy, Queen's University, Kingston, Ontario, Canada K7L 3N6;Department of Physics, Royal Military College of Canada, PO Box 17000, Station 'Forces', Kingston, Ontario, Canada K7K 7B4;GEPI, Observatoire de Paris, CNRS, place Jules Janssen, 92190 Meudon Cedex, France;Astronomical Institute 'Anton Pannekoek', University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands;Département de physique, génie physique et optique, CRAQ, UniversitéLaval, Québec, Canada G1K 7P4;GEPI, Observatoire de Paris, CNRS, UniversitéParis Diderot, 5 place Jules Janssen, 92190 Meudon, France;Royal Observatory of Belgium, 3 avenue circulaire, 1180 Brussels, Belgium;Shelyak Instruments, Les Roussets, 38420 Revel, France |
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| Abstract: | We have obtained 40 high-resolution circular spectropolarimetric measurements of 12 slowly pulsating B (SPB) stars, eight β Cephei stars and two Be stars with the Echelle Spectropolarimetric Device for the Observation of Stars at CFHT (ESPaDOnS) and Narval spectropolarimeters. The aim of these observations is to evaluate recent claims of a high incidence of magnetic field detections in stars of these types obtained using low-resolution spectropolarimetry by Hubrig et al. The precision achieved is generally comparable to or superior to that obtained by Hubrig et al., although our new observations are distinguished by their resolution of metallic and He line profiles, and their consequent sensitivity to magnetic fields of zero net longitudinal component. In the SPB stars, we confirm the detection of magnetic field in one star (16 Peg), but find no evidence of the presence of fields in the remaining 11. In the β Cep stars, we detect a field in ξ1 CMa, but not in any of the remaining seven stars. Finally, neither of the two B-type emission-line stars shows any evidence of magnetic field. Based on our results, we conclude that fields are not common in SPB, β Cep and B-type emission-line stars, consistent with the general rarity of fields in the broader population of main sequence B-type stars. A relatively small, systematic underestimation of the error bars associated with the UV Focal Reducer and Low Dispersion Spectrograph for the Very Large Telescope (FORS1) longitudinal field measurements of Hubrig et al. could in large part explain the discrepancy between their results and those presented here. |
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| Keywords: | stars: magnetic fields stars: pulsations |
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