Weak magnetic field, solid-envelope rotation, and wave-induced N-enrichment in the SPB star zeta Cassiopeiae
peer reviewed Aims. The main-sequence B-type star zeta Cassiopeiae is known as a N-rich star with a magnetic field discovered with the Musicos spectropolarimeter. We model the magnetic field of the star by means of 82 new spectropolarimetric observations of higher precision to investigate the field...
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2016
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Online Access: | https://orbi.uliege.be/handle/2268/193017 https://orbi.uliege.be/bitstream/2268/193017/1/zetacas_paper_aa27751-15.pdf https://doi.org/10.1051/0004-6361/201527751 |
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ftorbi:oai:orbi.ulg.ac.be:2268/193017 2024-04-21T08:13:08+00:00 Weak magnetic field, solid-envelope rotation, and wave-induced N-enrichment in the SPB star zeta Cassiopeiae Briquet, Maryline Neiner, C. Petit, P. Leroy, B. de Batz, B. MiMeS collaboration 2016-03 https://orbi.uliege.be/handle/2268/193017 https://orbi.uliege.be/bitstream/2268/193017/1/zetacas_paper_aa27751-15.pdf https://doi.org/10.1051/0004-6361/201527751 en eng EDP Sciences http://adsabs.harvard.edu/abs/2016arXiv160104517B urn:issn:0004-6361 urn:issn:1432-0746 https://orbi.uliege.be/handle/2268/193017 info:hdl:2268/193017 https://orbi.uliege.be/bitstream/2268/193017/1/zetacas_paper_aa27751-15.pdf doi:10.1051/0004-6361/201527751 scopus-id:2-s2.0-84960389824 open access http://purl.org/coar/access_right/c_abf2 info:eu-repo/semantics/openAccess Astronomy and Astrophysics, 587, A126 (2016-03) Astrophysics - Solar and Stellar Astrophysics Physical chemical mathematical & earth Sciences Space science astronomy & astrophysics Physique chimie mathématiques & sciences de la terre Aérospatiale astronomie & astrophysique journal article http://purl.org/coar/resource_type/c_6501 info:eu-repo/semantics/article peer reviewed 2016 ftorbi https://doi.org/10.1051/0004-6361/201527751 2024-03-27T14:52:54Z peer reviewed Aims. The main-sequence B-type star zeta Cassiopeiae is known as a N-rich star with a magnetic field discovered with the Musicos spectropolarimeter. We model the magnetic field of the star by means of 82 new spectropolarimetric observations of higher precision to investigate the field strength, topology, and effect. Methods. We gathered data with the Narval spectropolarimeter installed at Télescope Bernard Lyot (TBL; Pic du Midi, France) and applied the least-squares deconvolution technique to measure the circular polarisation of the light emitted from zeta Cas. We used a dipole oblique rotator model to determine the field configuration by fitting the longitudinal field measurements and by synthesizing the measured Stokes V profiles. We also made use of the Zeeman-Doppler imaging technique to map the stellar surface and to deduce the difference in rotation rate between the pole and equator. Results. zeta Cas exhibits a polar field strength B_pol of 100-150 G, which is the weakest polar field observed so far in a massive main-sequence star. Surface differential rotation is ruled out by our observations and the field of zeta Cas is strong enough to enforce rigid internal rotation in the radiative zone according to theory. Thus, the star rotates as a solid body in the envelope. Conclusions. We therefore exclude rotationally-induced mixing as the cause of the surface N-enrichment. We discuss that the transport of chemicals from the core to the surface by internal gravity waves is the most plausible explanation for the nitrogen overabundance at the surface of zeta Cas. Article in Journal/Newspaper narval narval University of Liège: ORBi (Open Repository and Bibliography) Astronomy & Astrophysics 587 A126 |
institution |
Open Polar |
collection |
University of Liège: ORBi (Open Repository and Bibliography) |
op_collection_id |
ftorbi |
language |
English |
topic |
Astrophysics - Solar and Stellar Astrophysics Physical chemical mathematical & earth Sciences Space science astronomy & astrophysics Physique chimie mathématiques & sciences de la terre Aérospatiale astronomie & astrophysique |
spellingShingle |
Astrophysics - Solar and Stellar Astrophysics Physical chemical mathematical & earth Sciences Space science astronomy & astrophysics Physique chimie mathématiques & sciences de la terre Aérospatiale astronomie & astrophysique Briquet, Maryline Neiner, C. Petit, P. Leroy, B. de Batz, B. MiMeS collaboration Weak magnetic field, solid-envelope rotation, and wave-induced N-enrichment in the SPB star zeta Cassiopeiae |
topic_facet |
Astrophysics - Solar and Stellar Astrophysics Physical chemical mathematical & earth Sciences Space science astronomy & astrophysics Physique chimie mathématiques & sciences de la terre Aérospatiale astronomie & astrophysique |
description |
peer reviewed Aims. The main-sequence B-type star zeta Cassiopeiae is known as a N-rich star with a magnetic field discovered with the Musicos spectropolarimeter. We model the magnetic field of the star by means of 82 new spectropolarimetric observations of higher precision to investigate the field strength, topology, and effect. Methods. We gathered data with the Narval spectropolarimeter installed at Télescope Bernard Lyot (TBL; Pic du Midi, France) and applied the least-squares deconvolution technique to measure the circular polarisation of the light emitted from zeta Cas. We used a dipole oblique rotator model to determine the field configuration by fitting the longitudinal field measurements and by synthesizing the measured Stokes V profiles. We also made use of the Zeeman-Doppler imaging technique to map the stellar surface and to deduce the difference in rotation rate between the pole and equator. Results. zeta Cas exhibits a polar field strength B_pol of 100-150 G, which is the weakest polar field observed so far in a massive main-sequence star. Surface differential rotation is ruled out by our observations and the field of zeta Cas is strong enough to enforce rigid internal rotation in the radiative zone according to theory. Thus, the star rotates as a solid body in the envelope. Conclusions. We therefore exclude rotationally-induced mixing as the cause of the surface N-enrichment. We discuss that the transport of chemicals from the core to the surface by internal gravity waves is the most plausible explanation for the nitrogen overabundance at the surface of zeta Cas. |
format |
Article in Journal/Newspaper |
author |
Briquet, Maryline Neiner, C. Petit, P. Leroy, B. de Batz, B. MiMeS collaboration |
author_facet |
Briquet, Maryline Neiner, C. Petit, P. Leroy, B. de Batz, B. MiMeS collaboration |
author_sort |
Briquet, Maryline |
title |
Weak magnetic field, solid-envelope rotation, and wave-induced N-enrichment in the SPB star zeta Cassiopeiae |
title_short |
Weak magnetic field, solid-envelope rotation, and wave-induced N-enrichment in the SPB star zeta Cassiopeiae |
title_full |
Weak magnetic field, solid-envelope rotation, and wave-induced N-enrichment in the SPB star zeta Cassiopeiae |
title_fullStr |
Weak magnetic field, solid-envelope rotation, and wave-induced N-enrichment in the SPB star zeta Cassiopeiae |
title_full_unstemmed |
Weak magnetic field, solid-envelope rotation, and wave-induced N-enrichment in the SPB star zeta Cassiopeiae |
title_sort |
weak magnetic field, solid-envelope rotation, and wave-induced n-enrichment in the spb star zeta cassiopeiae |
publisher |
EDP Sciences |
publishDate |
2016 |
url |
https://orbi.uliege.be/handle/2268/193017 https://orbi.uliege.be/bitstream/2268/193017/1/zetacas_paper_aa27751-15.pdf https://doi.org/10.1051/0004-6361/201527751 |
genre |
narval narval |
genre_facet |
narval narval |
op_source |
Astronomy and Astrophysics, 587, A126 (2016-03) |
op_relation |
http://adsabs.harvard.edu/abs/2016arXiv160104517B urn:issn:0004-6361 urn:issn:1432-0746 https://orbi.uliege.be/handle/2268/193017 info:hdl:2268/193017 https://orbi.uliege.be/bitstream/2268/193017/1/zetacas_paper_aa27751-15.pdf doi:10.1051/0004-6361/201527751 scopus-id:2-s2.0-84960389824 |
op_rights |
open access http://purl.org/coar/access_right/c_abf2 info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1051/0004-6361/201527751 |
container_title |
Astronomy & Astrophysics |
container_volume |
587 |
container_start_page |
A126 |
_version_ |
1796933673687187456 |