Novo cronômetro estelar a partir da análise de curvas de luz TESS de estrelas gêmeas solares
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Tipo
Dissertação
Data de publicação
2020-10-27
Periódico
Citações (Scopus)
Autores
Ponte, Geisa Teixeira da
Orientador
Valio, Adriana Benetti Marques
Título da Revista
ISSN da Revista
Título de Volume
Membros da banca
Moreno, Jorge Luis Meléndez
Simões, Paulo José Aguiar
Simões, Paulo José Aguiar
Programa
Ciências e Aplicações Geoespaciais
Resumo
The variability seen in the brightness of stars on timescale of days is often attributed
to the crossing of dark spots on the surface as the star rotates. Stellar activity, known
to be associated with the occurrence of spots, depends on the age of the star. Younger
stars tend to be much more active and this activity decreases as the stars age. To explore
a possible new stellar age indicator, we analyzed the photometric variability of 30 solar
twins using 2min cadence light curves of the TESS/NASA space mission. This valuable
dataset may help to understand the implications of the variability of magnetic activity
in exoplanet research and the concept of habitability. For that, we built a photometric
amplitude index ATESS directly correlated with the average index of chromospheric activity
logR0
HK, analyzed via precise atmospheric parameters derived from HARPS/ESO spectra.
These relations use the rotational modulation observed in TESS light curves due to active
regions on the stellar surfaces, consisting of stellar spots and faculae, as a function of activity
levels. We built a new tool in Python that optimizes the removal of TESS instrumental
systematics, maximizing the analysis of the amplitude of the photometric variability due to
the passage of active regions on the star surface. We also analyzed the Sun using 22 years
of TSI observations by VIRGO/SOHO. Our results show that the photometric amplitudes
are strongly correlated with the levels of chromospheric activity of the solar twin stars in
our sample, showing a very clear relationship also with their ages. We demonstrate that the
Sun is an ordinary star within this scenario, presenting a behavior as expected due to its
activity level and well-established age. This result is in agreement with the literature which
established a very robust relationship between age and activity of solar twins. Finally, we
understand that the ATESS can be used as an index of chromospheric activity, as well as a
stellar chronometer for solar twin stars observed by TESS.
Descrição
Palavras-chave
estrelas , atividade , tipo solar , técnicas , fotometria
Assuntos Scopus
Citação
PONTE, Geisa Teixeira da. Novo cronômetro estelar a partir da análise de curvas de luz TESS de estrelas gêmeas solares. 2020.71 f.. Dissertação( Ciências e Aplicações Geoespaciais) - Universidade Presbiteriana Mackenzie,São Paulo.