Sobre o comportamento rotacional das estrelas evoluídas de classe de luminosidade IV, III, II e Ib

• Ano de defesa: 2015
• Autor(a) principal: Oliveira, Luciano Luiz Alencar de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Brasil; UFRN; PROGRAMA DE PÓS-GRADUAÇÃO EM FÍSICA
• Palavras-chave em Português: Estrelas evoluídas - rotação estelar - massa estelar - descontinuidade rotacional.; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA
• Link de acesso: https://repositorio.ufrn.br/jspui/handle/123456789/21586

Rotation is one of the most important observable in stellar astronomy, driving largely the formation and evolution of stars. Indeed, the main challenging goal in the study of stellar rotation is the understanding of the angular momentum history once stars evolve along the HR diagram, as well the role of rotation in different dynamical phenomena including the stellar magnetic activity, accretion and coalescence processes. The present work brings unprecedented analysis of rotation along the HR diagram, on the basis of a complete sample of evolved stars, namely stars of luminosity classes Ib, II, III and IV, respectively supergiants, bright giants, giants and subgiants. For the rotational diagnostic, we use projected rotational velocity computed from observations carried out with of the CORAVEL spectrometers (Baranne et al. 1979) and presented in different catalogs (De Medeiros and Mayor (1999); De Medeiros et al. (2002) and De Medeiros et al. (2014). For the first time an evolutionary study of rotation is presented for single and multiple stars. We confirm that the rotation of single stars decrease sharply from spectral type F to G, at a rate depending on luminosity class and stellar mass. From G to K spectral regions rotation decreases smoothly for both luminosity classes. The present study reveals also the extent of the effects of tidal synchronization on stellar rotation, in binary systems with evolved components. For all the analysed luminosity classes we detect enhanced rotation in the G and K spectral regions, with values up to 70 km/s.