Publication
Title
The magnetic field of the B1/B2V star σ Lup
Author
Institution/Organisation
MiMeS Collaboration
Abstract
 The ultraviolet stellar wind lines of the photometrically periodic variable early B-type star sigma Lupi were found to behave very similarly to what has been observed in known magnetic B stars, although no periodicity could be determined. AAT spectropolarimetric measurements with SEMPOL were obtained. We detected a longitudinal magnetic field with varying strength and amplitude of about 100 G with error bars of typically 20 G. This type of variability supports an oblique magnetic rotator model. We fold the equivalent width of the 4 usable UV spectra in phase with the well-known photometric period of 3.019 days, which we identify with the rotation period of the star. The magnetic field variations are consistent with this period. Additional observations with ESPaDOnS attached to the CFHT strongly confirmed this discovery, and allowed to determine a precise magnetic period. Like in the other magnetic B stars the wind emission likely originates in the magnetic equatorial plane, with maximum emission occurring when a magnetic pole points towards the Earth. The 3.0182 d magnetic rotation period is consistent with the photometric period, with maximum light corresponding to maximum magnetic field. No helium or other chemical peculiarity is known for this object.
Language
English
Source (journal)
Proceedings of the International Astronomical Union
Source (book)
272nd Symposium of the International-Astronomical-Union on Active OB, Stars: Structure, Evolution, Mass-Loss, and Critical Limits, JUL 19-23, 2010, Paris, FRANCE
Publication
Cambridge : Cambridge univ press, 2011
ISBN
978-0-521-19840-0
Volume/pages
272(2011), p. 192-193
ISI
000294438200039
Full text (Publisher's DOI)
Full text (publisher's version - intranet only)
UAntwerpen
 Publication type Subject