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What can magnetic early B-type stars tell us about early B-type stars in general?

Published online by Cambridge University Press:  28 July 2017

Matthew Shultz ,
Gregg Wade ,
Thomas Rivinius ,
Coralie Neiner ,
Evelyne Alecian ,
Véronique Petit ,
Jason Grunhut  and
the MiMeS & BinaMIcS Collaborations
Matthew Shultz
Affiliation:
Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala 75120 email: matthew.shultz@physics.uu.se
Gregg Wade
Affiliation:
Department of Physics, Royal Military College of Canada, Kingston, Ontario K7K 7B4, Canada
Thomas Rivinius
Affiliation:
ESO - European Organisation for Astronomical Research in the Southern Hemisphere, Casilla 19001, Santiago 19, Chile
Coralie Neiner
Affiliation:
LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, 92195 Meudon, France
Evelyne Alecian
Affiliation:
Université Grenoble Alpes, IPAG, F-38000 Grenoble, France CNRS, IPAG, F-38000 Grenoble, France LESIA, Observatoire de Paris, CNRS UMR 8109, UPMC, Université Paris Diderot, 5 place Jules Janssen, 92190, Meudon, France
Véronique Petit
Affiliation:
Department of Physics and Astronomy, University of Delaware, 217 Sharp Lab, Newark, DE 19716, USA
Jason Grunhut
Affiliation:
Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON, M5S 3H4, Canada
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Abstract

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Some magnetic early B-type stars display Hα emission originating in their Centrifugal Magnetospheres (CMs). To determine the rotational and magnetic properties necessary for the onset of emission, we analyzed a large spectropolarimetric dataset for a sample of 51 B5-B0 magnetic stars. New rotational periods were found for 15 stars. We determined physical parameters, dipolar magnetic field strengths, magnetospheric parameters, and magnetic braking timescales. Hα-bright stars are more rapidly rotating, more strongly magnetized, and younger than the overall population. We use the high sensitivity of magnetic braking to the mass-loss rate to test the predictions of Vink et al. (2001) and Krtička (2014) by comparing ages t to maximum spindown ages tS, max. For stars with M* < 10 M⊙ this comparison favours the Krtička recipe. For the most massive stars, both prescriptions yield t ≪ tS, max, a discrepancy which is difficult to explain via incorrect mass-loss rates alone.

Keywords

stars: magnetic fieldsstars: mass lossstars: rotationstars: early-type
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 12 , Symposium S329: The Lives and Death-Throes of Massive Stars , November 2016 , pp. 126 - 130
Copyright
Copyright © International Astronomical Union 2017 

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