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“Stellar Prominences” on OB starsto explain wind-line variability

Published online by Cambridge University Press:  07 August 2014

H. F. Henrichs
Affiliation:
Astronomical Institute Anton Pannekoek, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands email: h.f.henrichs@uva.nl
N. P. Sudnik
Affiliation:
Sobolev Astronomical Institute, Saint Petersburg State University, Universitetskij pr. 28, Staryj Peterhof, 198504, Saint Petersburg, Russia email: snata.astro@gmail.com
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Abstract

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Many O and B stars show unexplained cyclical variability in their winds, i.e. modulation of absorption features on the rotational timescale, but not strictly periodic over longer timescales. For these stars no dipolar magnetic fields have been detected, with upper limits below 300 G. Similar cyclical variability is also found in many optical lines, which are formed at the base of the wind. We propose that these cyclical variations are caused by the presence of multiple, transient, short-lived, corotating magnetic loops, which we call “stellar prominences”. We present a simplified model representing these prominences to explain the cyclical optical wind-line variability in the O supergiant λ Cephei. Other supporting evidence for such prominences comes from the recent discovery of photometric variability in a comparable O star, which was explained by the presence of multiple transient bright spots, presumably of magnetic origin as well.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2014 

References

Cantiello, M., Langer, N., Brott, I., de Koter, A., Shore, S. N., et al., 2009 A&A, 499, 279Google Scholar
Cantiello, M. & Braithwaite, J., 2011, A&A, 543, 140Google Scholar
Cranmer, S. R. & Owocki, S. A., 1994, ApJ, 462, 469Google Scholar
de Jong, J. A., Henrichs, H. F., Schrijvers, C., Gies, D. R., et al., 1999, A&A, 345, 172Google Scholar
de Jong, J. A., Henrichs, H. F., Kaper, L., Nichols, J. S., et al., 2001, A&A, 368, 601Google Scholar
Donati, J.-F., Babel, J., Harries, T. J., et al., 2002, MNRAS, 333, 55Google Scholar
Henrichs, H. F., 1999, Lecture Notes in Physics, Berlin Springer Verlag, 523, 305Google Scholar
Henrichs, H. F., Kaper, L. & Zwarthoed, G. A. A., 1988 In ESA, Proc. a Decade of UV Astronomy with the IUE Satellite, Volume 2, 145Google Scholar
Henrichs, H. F., Kaper, L., & Nichols, J. S., 1994, A&A, 285, 565Google Scholar
Kaper, L., Henrichs, H. F., Nichols, J. S., et al., 1996, A&ASS, 116, 257Google Scholar
Kaper, L., Henrichs, H. F., Fullerton, A. W., et al., 1997, A&A, 327, 281Google Scholar
Kaper, L., Henrichs, H. F., Nichols, J. S., & Telting, J. H., 1999, A&A, 344, 231Google Scholar
Kochukhov, O. & Sudnik, N., 2013, A&A, 554, 93Google Scholar
Markova, N., Puls, J., Repolust, T., & Markov, H., 2004, A&A, 413, 693Google Scholar
Massa, D., Fullerton, A. W., Nichols, J. S., et al., 1995, ApJ, 452, L53Google Scholar
Prinja, R. K., 1988, MNRAS 231, 21PCrossRefGoogle Scholar
Prinja, R. K. & Howarth, I. D., 1986, ApJS 61, 357Google Scholar
Ramiaramanantsoa, T., Moffat, A. F. J., Chené, A.-N., Desforges, S., Richardson, N. D., Henrichs, H. F., Guenther, D. B., & Kuschnig, R., et al., 2013, MNRAS submittedGoogle Scholar
ud-Doula, A., & Owocki, S. P., 2002, ApJ, 576, 413Google Scholar
Walker, G. A. H., Kuschnig, R., Matthews, J. M., et al., 2005, ApJL, 623, L145Google Scholar