A FOURIER TRANSFORM METHOD for V sin i ESTIMATIONS UNDER NONLINEAR LIMB-DARKENING LAWS

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dc.contributor.author Levenhagen, Ronaldo Savarino [UNIFESP]
dc.date.accessioned 2016-01-24T14:38:18Z
dc.date.available 2016-01-24T14:38:18Z
dc.date.issued 2014-12-10
dc.identifier http://dx.doi.org/10.1088/0004-637X/797/1/29
dc.identifier.citation Astrophysical Journal. Bristol: Iop Publishing Ltd, v. 797, n. 1, 10 p., 2014.
dc.identifier.issn 0004-637X
dc.identifier.uri http://repositorio.unifesp.br/handle/11600/38550
dc.description.abstract Star rotation offers us a large horizon for the study of many important physical issues pertaining to stellar evolution. Currently, four methods are widely used to infer rotation velocities, namely those related to line width calibrations, on the fitting of synthetic spectra, interferometry, and on Fourier transforms (FTs) of line profiles. Almost all of the estimations of stellar projected rotation velocities using the Fourier method in the literature have been addressed with the use of linear limb-darkening (LD) approximations during the evaluation of rotation profiles and their cosine FTs, which in certain cases, lead to discrepant velocity estimates. in this work, we introduce new mathematical expressions of rotation profiles and their Fourier cosine transforms assuming three nonlinear LD laws-quadratic, square-root, and logarithmic-and study their applications with and without gravity-darkening (GD) and geometrical flattening (GF) effects. Through an analysis of He I models in the visible range accounting for both limb and GD, we find out that, for classical models without rotationally driven effects, all the V sin i values are too close to each other. On the other hand, taking into account GD and GF, the V sin i obtained with the linear law result in V sin i values that are systematically smaller than those obtained with the other laws. As a rule of thumb, we apply these expressions to the FT method to evaluate the projected rotation velocity of the emission B-type star Achernar (alpha Eri). en
dc.description.sponsorship Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.description.sponsorship Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.format.extent 10
dc.language.iso eng
dc.publisher Iop Publishing Ltd
dc.relation.ispartof Astrophysical Journal
dc.rights Acesso aberto
dc.subject methods: observational en
dc.subject stars: activity en
dc.subject stars: atmospheres en
dc.subject stars: emission-line, Be en
dc.subject stars: fundamental parameters en
dc.subject stars: individual (Achernar) en
dc.subject stars: rotation en
dc.title A FOURIER TRANSFORM METHOD for V sin i ESTIMATIONS UNDER NONLINEAR LIMB-DARKENING LAWS en
dc.type Artigo
dc.rights.license http://iopscience.iop.org/page/copyright
dc.contributor.institution Universidade Federal de São Paulo (UNIFESP)
dc.description.affiliation Universidade Federal de São Paulo, Dept Ciencias Exatas & Terra, BR-09972270 Diadema, SP, Brazil
dc.description.affiliationUnifesp Universidade Federal de São Paulo, Dept Ciencias Exatas & Terra, BR-09972270 Diadema, SP, Brazil
dc.description.sponsorshipID CNPq: 307660/2011-7
dc.description.sponsorshipID CNPq: 307095/2008-8
dc.description.sponsorshipID FAPESP: 04/14256-8
dc.description.sponsorshipID FAPESP: 00/10029-6
dc.description.sponsorshipID FAPESP: 1998/10138-8
dc.identifier.file WOS000345915000029.pdf
dc.identifier.doi 10.1088/0004-637X/797/1/29
dc.description.source Web of Science
dc.identifier.wos WOS:000345915000029



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