Campos magnéticos de estrelas G-K e Dividing Lines no Diagrama HR

We investigate the surface magnetic field of 35 G-K stars. In our sample, 14 stars present moderate to strong signs of magnetic activity, as known from the literature. Other 7 stars seem not to have been through thermohaline mixing, which could be due to hosting a strong magnetic field. Subsequently...

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Autor principal:	Silva, Marina Tatiane Ribeiro da
Outros Autores:	Costa, Jefferson Soares da
Formato:	bachelorThesis
Idioma:	pt_BR
Publicado em:	Universidade Federal do Rio Grande do Norte
Assuntos:	Campo Magnético, Diagrama HR, Dividing Line, LSD.
Endereço do item:	https://repositorio.ufrn.br/handle/123456789/40225
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id	ri-123456789-40225
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spelling	ri-123456789-402252021-09-29T13:00:08Z Campos magnéticos de estrelas G-K e Dividing Lines no Diagrama HR Silva, Marina Tatiane Ribeiro da Costa, Jefferson Soares da Campo Magnético, Diagrama HR, Dividing Line, LSD. We investigate the surface magnetic field of 35 G-K stars. In our sample, 14 stars present moderate to strong signs of magnetic activity, as known from the literature. Other 7 stars seem not to have been through thermohaline mixing, which could be due to hosting a strong magnetic field. Subsequently, we observed 14 additional very bright stars which allowed us to improve our ability with spectropolarimetry. Lastly, we analysed the existence of dividing lines in the Hertzsprung-Russell diagram. Using the data from spectropolarimeters NARVAL and ESPaDOnS, it was possible to detect circular polarisation within the photospheric absorption lines of our targets. Here, we use the Least-Squares Deconvolution (LSD) method to create high signal-to-noise ratio mean Stokes V profiles. Then, we detect the magnetic field and evaluate its relation to the dividing lines in the HR diagram. The presence of the dividing line in the HR diagram causes the late-type stars to divide into two groups. To the left, we find solar-type stars, with an atmospheric structure composed by chromosphere, transition region, crown and solar-type winds. To the right, the stars have extended chromosphere and heavy cold winds. We unquestionably determined the surface magnetic field for 3 stars from our sample and concluded that other 18 of them show no detection of magnetic activity. The magnetic stars lie to the left of the dividing line, as the non-magnetic stars lie to the right of the line, showing evidence of affiliation between the magnetic field behaviour and the dividing line. Investigamos o campo magnético superficial de 35 estrelas dos tipos espectrais G e K. Na nossa amostra, 14 estrelas são conhecidas na literatura por apresentarem sinais moderados a fortes de atividade magnética. 7 estrelas aparentam não ter passado pela mistura termohalina, o que poderia ser devido à presença de um campo magnético forte. Posteriormente, observamos 14 estrelas muito brilhantes que nos permitiram melhorar nossa habilidade com a espectropolarimetria. Por fim, analisamos a existência de dividing lines no diagrama Hertzsprung-Russell. Utilizando os dados dos espectropolarímetros NARVAL e ESPaDOnS, foi possível detectar a polarização circular dentro das linhas de absorção fotosféricas de nossos alvos. Aqui, usamos o método de Deconvolução em Mínimos Quadrados (LSD) para criar perfis médios de Stokes V com alta razão sinal- ruído. Então, detectamos o campo magnético e avaliamos sua relação com as dividing lines no diagrama HR. A presença da dividing line no diagrama HR faz com que as estrelas tardias sejam divididas em dois grupos. À esquerda, encontramos estrelas do tipo solar, com estrutura atmosférica composta por cromosfera, região de transição, coroa e ventos de tipo solar. À direita, podemos encontrar estrelas com extensa cromosfera e ventos massivos e frios. Determinamos, indubitavelmente, o campo magnético superficial de 3 estrelas da nossa amostra e concluímos que outras 18 delas não mostram detecção de atividade magnética. As estrelas magnéticas estão situadas à esquerda da dividing line, enquanto as estrelas não-magnéticas se encontram à direita da linha, mostrando evidências de afiliação entre o comportamento do campo magnético e a dividing line. 2018-01-10T16:14:23Z 2021-09-29T13:00:07Z 2018-01-10T16:14:23Z 2021-09-29T13:00:07Z 2017-12-08 bachelorThesis 2011058316 SILVA, Marina Tatiane Ribeiro da. Campos magnéticos de estrelas G-K e Dividing Lines no Diagrama HR. 2017. 54 f. Trabalho de Conclusão de Curso (Graduação em Física Bacharelado) - Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal, 2017. https://repositorio.ufrn.br/handle/123456789/40225 pt_BR openAccess application/pdf Universidade Federal do Rio Grande do Norte Brasil UFRN Física
institution	Repositório Institucional
collection	RI - UFRN
language	pt_BR
topic	Campo Magnético, Diagrama HR, Dividing Line, LSD.
spellingShingle	Campo Magnético, Diagrama HR, Dividing Line, LSD. Silva, Marina Tatiane Ribeiro da Campos magnéticos de estrelas G-K e Dividing Lines no Diagrama HR
description	We investigate the surface magnetic field of 35 G-K stars. In our sample, 14 stars present moderate to strong signs of magnetic activity, as known from the literature. Other 7 stars seem not to have been through thermohaline mixing, which could be due to hosting a strong magnetic field. Subsequently, we observed 14 additional very bright stars which allowed us to improve our ability with spectropolarimetry. Lastly, we analysed the existence of dividing lines in the Hertzsprung-Russell diagram. Using the data from spectropolarimeters NARVAL and ESPaDOnS, it was possible to detect circular polarisation within the photospheric absorption lines of our targets. Here, we use the Least-Squares Deconvolution (LSD) method to create high signal-to-noise ratio mean Stokes V profiles. Then, we detect the magnetic field and evaluate its relation to the dividing lines in the HR diagram. The presence of the dividing line in the HR diagram causes the late-type stars to divide into two groups. To the left, we find solar-type stars, with an atmospheric structure composed by chromosphere, transition region, crown and solar-type winds. To the right, the stars have extended chromosphere and heavy cold winds. We unquestionably determined the surface magnetic field for 3 stars from our sample and concluded that other 18 of them show no detection of magnetic activity. The magnetic stars lie to the left of the dividing line, as the non-magnetic stars lie to the right of the line, showing evidence of affiliation between the magnetic field behaviour and the dividing line.
author2	Costa, Jefferson Soares da
author_facet	Costa, Jefferson Soares da Silva, Marina Tatiane Ribeiro da
format	bachelorThesis
author	Silva, Marina Tatiane Ribeiro da
author_sort	Silva, Marina Tatiane Ribeiro da
title	Campos magnéticos de estrelas G-K e Dividing Lines no Diagrama HR
title_short	Campos magnéticos de estrelas G-K e Dividing Lines no Diagrama HR
title_full	Campos magnéticos de estrelas G-K e Dividing Lines no Diagrama HR
title_fullStr	Campos magnéticos de estrelas G-K e Dividing Lines no Diagrama HR
title_full_unstemmed	Campos magnéticos de estrelas G-K e Dividing Lines no Diagrama HR
title_sort	campos magnéticos de estrelas g-k e dividing lines no diagrama hr
publisher	Universidade Federal do Rio Grande do Norte
publishDate	2018
url	https://repositorio.ufrn.br/handle/123456789/40225
work_keys_str_mv	AT silvamarinatatianeribeiroda camposmagneticosdeestrelasgkedividinglinesnodiagramahr
_version_	1773965343613517824

Campos magnéticos de estrelas G-K e Dividing Lines no Diagrama HR

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