On the incidence of magnetic fields in slowly pulsating B, β Cephei and B-type emission-line stars

Abstract

We have obtained 40 high-resolution circular spectropolarimetric measurements\nof 12 slowly-pulsating B (SPB) stars, 8 Beta Cephei stars and two Be stars with\nthe ESPaDOnS and NARVAL spectropolarimeters. The aim of these observations is\nto evaluate recent claims of a high incidence of magnetic field detections in\nstars of these types obtained using low-resolution spectropolarimetry by Hubrig\n(2006), Hubrig (2007) and Hubrig (2009). The precision achieved is generally\ncomparable to or superior to that obtained by Hubrig et al., although our new\nobservations are distinguished by their resolution of metallic and He line\nprofiles, and their consequent sensitivity to magnetic fields of zero net\nlongitudinal component. In the SPB stars we confirm the detection of magnetic\nfield in one star (16 Peg), but find no evidence of the presence of fields in\nthe remaining 11. In the Beta Cep stars, we detect a field in xi^1 CMa, but not\nin any of the remaining 7 stars. Finally, neither of the two B-type emission\nline stars shows any evidence of magnetic field. Based on our results, we\nconclude that fields are not common in SPB, Beta Cep and B-type emission line\nstars, consistent with the general rarity of fields in the broader population\nof main sequence B-type stars.\n