| Grant number: | 16/20667-8 |
| Support Opportunities: | Scholarships in Brazil - Post-Doctoral |
| Start date: | April 01, 2017 |
| End date: | August 31, 2021 |
| Field of knowledge: | Physical Sciences and Mathematics - Astronomy - Stellar Astrophysics |
| Agreement: | Coordination of Improvement of Higher Education Personnel (CAPES) |
| Principal Investigator: | Jorge Luis Melendez Moreno |
| Grantee: | Diego Lorenzo de Oliveira |
| Host Institution: | Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
| Associated research grant: | 18/04055-8 - High precision spectroscopy: from the first stars to planets, AP.TEM |
Abstract Our main goal is to study the impact of stellar abundances and other atmospheric parameters on the determination of chromospheric activity levels traced by different spectroscopic indicators such as: Ca II & K, Na I dublet, Halpha, Hbeta and Ca II infrared triplet lines. This study will use chromospheric fluxes to obtain stellar ages through age-activity relations. As a result, we plan to: 1) characterize comprehensively the chromospheric activity phenomena, exploring the correlations between the chromospheric activity indicators (flux-flux relations); 2) investigate the relationship between the stellar activity level, stellar rotation and the convective mixing processes traced by lithium depletion in solar-type stars. To this end, we will derive chromospheric absolute fluxes based on modern theoretical models of stellar atmospheres Lorenzo-Oliveira et al. 2016 for a benchmark sample of 88 solar twins (Ramírez et al. 2014) with high-precision spectroscopic parameters(sigma(Teff) = 7 K, sigma([Fe/H]) = 0.01 dex and sigma(log g) = 0.02 dex). Moreover, in order to extend the relations derived for solar twins, we compiled high spectral resolution and signal-to-noise ratio spectra for a large ancillary sample of solar-type stars within a broad range of masses and metallicities. Precise atmospheric parameters (Teff, [Fe/H] and log g) will be determined for these stars in the light of detailed spectroscopic line-by-line analysis (excitation and ionisation equilibria of Fe I and Fe II lines) and evolutionary parameters will be estimated through HR diagrams. Our final goal is to provide the most reliable activity-age relations for age dating. (AU) | |
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