| Texto completo | |
| Autor(es): |
Levenhagen, R. S.
[1]
Número total de Autores: 1
|
| Afiliação do(s) autor(es): | [1] Univ Fed Sao Paulo, Dept Ciencias Exatas & Terra, BR-09972270 Diadema, SP - Brazil
Número total de Afiliações: 1
|
| Tipo de documento: | Artigo Científico |
| Fonte: | ASTROPHYSICAL JOURNAL; v. 797, n. 1 DEC 10 2014. |
| Citações Web of Science: | 2 |
| Resumo | |
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). (AU) | |
| Processo FAPESP: | 98/10138-8 - Espectroscopia de média e alta resolução: abundâncias químicas e populações estelares |
| Beneficiário: | Beatriz Leonor Silveira Barbuy |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |
| Processo FAPESP: | 00/10029-6 - Estrelas "be": formacao e estrutura de seus envelopes circunstelares. |
| Beneficiário: | Ronaldo Savarino Levenhagen |
| Modalidade de apoio: | Bolsas no Brasil - Doutorado |
| Processo FAPESP: | 04/14256-8 - Estudo de estrelas B e Be pertencentes ao halo galáctico |
| Beneficiário: | Ronaldo Savarino Levenhagen |
| Modalidade de apoio: | Bolsas no Brasil - Pós-Doutorado |