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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Efeitos do freio magn?tico sobre a distribui??o da rota??o estelar

Silva Sobrinho, Rodrigo da 21 May 2015 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-03-31T23:35:39Z No. of bitstreams: 1 RodrigoDaSilvaSobrinho_DISSERT.pdf: 2479618 bytes, checksum: 3094f42c505921ebc1ac094112499a49 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-04-05T20:34:51Z (GMT) No. of bitstreams: 1 RodrigoDaSilvaSobrinho_DISSERT.pdf: 2479618 bytes, checksum: 3094f42c505921ebc1ac094112499a49 (MD5) / Made available in DSpace on 2016-04-05T20:34:51Z (GMT). No. of bitstreams: 1 RodrigoDaSilvaSobrinho_DISSERT.pdf: 2479618 bytes, checksum: 3094f42c505921ebc1ac094112499a49 (MD5) Previous issue date: 2015-05-21 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / O pioneiro trabalho proposto por Skumanich (1972) mostrou que a velocidade de rota?c?ao projetada m?edia < v sini > para estrelas do tipo solar obedece uma lei de decrescimento no tempo, dada por t ?1/2 , onde t ?e a idade da estrela. Essa rela?c?ao ?e consistente com as teorias de perda de momentum angular atrav?es do vento estelar ionizado, que por sua vez est?a acoplado `a estrela pelo seu campo magn?etico. V?arios autores (e.g.: Silva et al. 2013 e de Freitas et al. 2014) analisaram as poss??veis correla?c?oes entre o decaimento rotacional e o perfil da distribui?c?ao de velocidade. Esses autores chegaram a uma simples rela?c?ao heur??stica, mas n?ao constru??ram uma passagem direta entre o expoente do decaimento rotacional (j) e o expoente da distribui?c?ao da velocidade rotacional (q). Todo esse cen?ario te?orico foi proposto usando uma eficiente e robusta mec?anica estat??stica bem conhecida como mec?anica estat??stica n?ao-extensiva. A presente disserta?c?ao prop?oe efetivamente fechar essa quest?ao, elaborando um caminho te?orico para modificar as distribui?c?oes q-Maxwellianas em q-Maxwellianas com v??nculos f??sicos extra??dos da teoria do freio magn?etico. Para testar nossas distribui?c?oes, usamos um pacote de dados do cat?alogo de Geneva-Copenhagem Survey com aproximadamente 6000 estrelas F e G limitadas em idade. Como resultado, obtivemos que os expoentes da lei de decaimento e da distribui?c?ao seguem uma rela?c?ao similar `aquela proposta por Silva et al. (2013). / The pioneering work proposed by Skumanich (1972) has shown that the projected mean rotational velocity < v sini > for solar type stars follows a rotation law decreases with the time given by t ?1/2 , where t is the stellar age. This relationship is consistent with the theories of the angular momentum loss through the ionized stellar wind, which in turn is coupled to the star through its magnetic field. Several authors (e.g.: Silva et al. 2013 and de Freitas et al. 2014) have analyzed the possible matches between the rotational decay and the profile of the velocity distribution. These authors came to a simple heuristic relationship, but did not build a direct path between the exponent of the rotational decay (j) and the exponent of the distribution of the rotational velocity (q). The whole theoretical scenario has been proposed using an efficient and strong statistical mechanics well known as non-extensive statistical mechanics. The present dissertation proposes effectively to close this issue by elaborating a theoretical way to modify the q-Maxwellians? distributions into q-Maxwellians with physics links extracted from the theory of magnetic braking. In order to test our distributions we have used the GenevaCapenhagen Survey data with approximately 6000 F and G field stars limited by age. As a result, we obtained that the exponents of the decay law and distribution follow a similar relationship to that proposed by Silva et al. (2013).

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