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Article: An analysis of the rapidly rotating Bp star HD 133880

TitleAn analysis of the rapidly rotating Bp star HD 133880
Authors
KeywordsChemically peculiar
Stars: magnetic field
Stars: stars: abundances
Issue Date2012
PublisherBlackwell Publishing Ltd. The Journal's web site is located at http://www.blackwellpublishing.com/journals/MNR
Citation
Monthly Notices of The Royal Astronomical Society, 2012, v. 423 n. 1, p. 328-343 How to Cite?
AbstractHD 133880 is a rapidly rotating chemically peculiar B-type (Bp) star (vsini≃ 103kms -1) and is host to one of the strongest magnetic fields of any Ap/Bp star. A member of the Upper Centaurus Lupus association, it is a star with a well-determined age of 16Myr. 12 new spectra, four of which are polarimetric, obtained from the FEROS, ESPaDOnS and HARPS instruments, provide sufficient material from which to re-evaluate the magnetic field and obtain a first approximation to the atmospheric abundance distributions of He, O, Mg, Si, Ti, Cr, Fe, Ni, Pr and Nd. An abundance analysis was carried out using zeeman, a program which synthesizes spectral line profiles for stars with permeating magnetic fields. The magnetic field structure was characterized by a colinear multipole expansion from the observed variations of the longitudinal and surface fields with rotational phase. Both magnetic hemispheres are clearly visible during the stellar rotation, and thus a three-ring abundance distribution model encompassing both magnetic poles and magnetic equator with equal spans in colatitude was adopted. Using the new magnetic field measurements and optical photometry together with previously published data, we refine the period of HD 133880 to P= 0.877476 ± 0.000009d. Our simple axisymmetric magnetic field model is based on a predominantly quadrupolar component that roughly describes the field variations. Using spectrum synthesis, we derived mean abundances for O, Mg, Si, Ti, Cr, Fe and Pr. All elements, except Mg, are overabundant compared to the Sun. Mg appears to be approximately uniform over the stellar surface, while all other elements are more abundant in the negative magnetic hemisphere than in the positive magnetic hemisphere. In contrast to most Ap/Bp stars which show an underabundance in O, in HD 133880 this element is clearly overabundant compared to the solar abundance ratio. In studying the Hα and Paschen lines in the optical spectra, we could not unambiguously detect information about the magnetosphere of HD 133880. However, radio emission data at both 3 and 6cm suggest that the magnetospheric plasma is held in rigid rotation with the star by the magnetic field and further supported against collapse by the rapid rotation. Subtle differences in the shapes of the optically thick radio light curves at 3 and 6cm suggest that the large-scale magnetic field is not fully axisymmetric at large distances from the star. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.
Persistent Identifierhttp://hdl.handle.net/10722/146416
ISSN
2015 Impact Factor: 4.952
2015 SCImago Journal Rankings: 2.806
ISI Accession Number ID
Funding AgencyGrant Number
Natural Sciences and Engineering Research Council of Canada
European Southern Observatory (ESO) from the ESO/ST-ECF Science Archive Facility082.D-0061(A)
083.D-0034(A)
085.D-0296(A)
086.D-0449(A)
Funding Information:

JDB, JDL and GW are grateful for support by the Natural Sciences and Engineering Research Council of Canada. We thank Veronique Petit for communicating calculations of the magnetospheric parameters for HD 133880 prior to publication. We thank the HARPSpol team for generously providing a spectrum for HD 133880 used in this analysis. We thank the referee, Dr Evelyne Alecian, for her useful comments and suggestions.

References

 

DC FieldValueLanguage
dc.contributor.authorBailey, JDen_HK
dc.contributor.authorGrunhut, Jen_HK
dc.contributor.authorShultz, Men_HK
dc.contributor.authorWade, Gen_HK
dc.contributor.authorLandstreet, JDen_HK
dc.contributor.authorBohlender, Den_HK
dc.contributor.authorLim, Jen_HK
dc.contributor.authorWong, Ken_HK
dc.contributor.authorDrake, Sen_HK
dc.contributor.authorLinsky, Jen_HK
dc.date.accessioned2012-04-24T07:52:16Z-
dc.date.available2012-04-24T07:52:16Z-
dc.date.issued2012en_HK
dc.identifier.citationMonthly Notices of The Royal Astronomical Society, 2012, v. 423 n. 1, p. 328-343en_HK
dc.identifier.issn0035-8711en_HK
dc.identifier.urihttp://hdl.handle.net/10722/146416-
dc.description.abstractHD 133880 is a rapidly rotating chemically peculiar B-type (Bp) star (vsini≃ 103kms -1) and is host to one of the strongest magnetic fields of any Ap/Bp star. A member of the Upper Centaurus Lupus association, it is a star with a well-determined age of 16Myr. 12 new spectra, four of which are polarimetric, obtained from the FEROS, ESPaDOnS and HARPS instruments, provide sufficient material from which to re-evaluate the magnetic field and obtain a first approximation to the atmospheric abundance distributions of He, O, Mg, Si, Ti, Cr, Fe, Ni, Pr and Nd. An abundance analysis was carried out using zeeman, a program which synthesizes spectral line profiles for stars with permeating magnetic fields. The magnetic field structure was characterized by a colinear multipole expansion from the observed variations of the longitudinal and surface fields with rotational phase. Both magnetic hemispheres are clearly visible during the stellar rotation, and thus a three-ring abundance distribution model encompassing both magnetic poles and magnetic equator with equal spans in colatitude was adopted. Using the new magnetic field measurements and optical photometry together with previously published data, we refine the period of HD 133880 to P= 0.877476 ± 0.000009d. Our simple axisymmetric magnetic field model is based on a predominantly quadrupolar component that roughly describes the field variations. Using spectrum synthesis, we derived mean abundances for O, Mg, Si, Ti, Cr, Fe and Pr. All elements, except Mg, are overabundant compared to the Sun. Mg appears to be approximately uniform over the stellar surface, while all other elements are more abundant in the negative magnetic hemisphere than in the positive magnetic hemisphere. In contrast to most Ap/Bp stars which show an underabundance in O, in HD 133880 this element is clearly overabundant compared to the solar abundance ratio. In studying the Hα and Paschen lines in the optical spectra, we could not unambiguously detect information about the magnetosphere of HD 133880. However, radio emission data at both 3 and 6cm suggest that the magnetospheric plasma is held in rigid rotation with the star by the magnetic field and further supported against collapse by the rapid rotation. Subtle differences in the shapes of the optically thick radio light curves at 3 and 6cm suggest that the large-scale magnetic field is not fully axisymmetric at large distances from the star. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.en_HK
dc.languageengen_US
dc.publisherBlackwell Publishing Ltd. The Journal's web site is located at http://www.blackwellpublishing.com/journals/MNRen_HK
dc.relation.ispartofMonthly Notices of the Royal Astronomical Societyen_HK
dc.rightsThe definitive version is available at www.blackwell-synergy.com-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.subjectChemically peculiaren_HK
dc.subjectStars: magnetic fielden_HK
dc.subjectStars: stars: abundancesen_HK
dc.titleAn analysis of the rapidly rotating Bp star HD 133880en_HK
dc.typeArticleen_HK
dc.identifier.emailLim, J: jjlim@hku.hken_HK
dc.identifier.authorityLim, J=rp00745en_HK
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.1111/j.1365-2966.2012.20881.xen_HK
dc.identifier.scopuseid_2-s2.0-84861652825en_HK
dc.identifier.hkuros199375en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-84861652825&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume423en_HK
dc.identifier.issue1en_HK
dc.identifier.spage328en_HK
dc.identifier.epage343en_HK
dc.identifier.isiWOS:000304599100026-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridBailey, JD=54379745100en_HK
dc.identifier.scopusauthoridGrunhut, J=23090670900en_HK
dc.identifier.scopusauthoridShultz, M=50761516400en_HK
dc.identifier.scopusauthoridWade, G=7101890468en_HK
dc.identifier.scopusauthoridLandstreet, JD=6701578913en_HK
dc.identifier.scopusauthoridBohlender, D=22633839300en_HK
dc.identifier.scopusauthoridLim, J=7403453870en_HK
dc.identifier.scopusauthoridWong, K=37056419600en_HK
dc.identifier.scopusauthoridDrake, S=7102438520en_HK
dc.identifier.scopusauthoridLinsky, J=35465341400en_HK

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