Stellar and Galactic Astrophysics

Characterization of Kepler's weak stars based on J-PLUS / J-PAS data

Keywords: Stars, Kepler, physical parameters, exoplanets, J-PLUS, J-PAS, S-PLUS

Advisor: Marcelo Borges Fernandes

Summary: The Kepler mission observed ~ 4.5 million stars, however, only the 150,000 brightest stars were analyzed continuously with the production of light curves, mainly to identify Earth-sized planets orbiting stars in the main sequence. For the analysis of the light curves of the weaker stars, a better characterization of these objects is still needed. From the data from the J-PLUS and J-PAS surveys, our goal is, using machine learning techniques, to obtain Teff, log g and [Fe / H] with a higher precision than in the literature. These parameters associated with empirical calibrations will also allow us to determine radii and stellar masses. With all these parameters well characterized, it will be possible to better infer the rate of exoplanets for stars with transits.

Requirements: Graduation in astronomy, physics and related areas

Blue Stars Identification through J-PAS / J-PLUS / S-PLUS Surveys

Keywords: Stars, physical parameters, machine learning, J-PAS, J-PLUS, S-PLUS

Advisor: Marcelo Borges Fernandes

Abstract: The group of stars known as "blue stars" is formed by hot sub-dwarfs, symbiotic stars, horizontal branch stars, cataclysmic variables, post-AGBs and planetary nebulae. As there are few objects of these classes identified in the halo of our Galaxy, there are still many doubts about the mechanisms of formation of these objects in low metallicity and their physical parameters. Therefore, it is essential to search for new objects and for this purpose surveys such as J-PAS, J-PLUS and S-PLUS become the ideal tools for this purpose. The analysis of multicolored data, in combination with data from the literature, through machine learning techniques, will enable us to obtain physical parameters and identify objects that are candidates for the different classes of blue stars.

Requirements: Graduation in Astronomy, Physics and related areas.

Analysis of B-star abundances of the NGC 3293 cluster based on GES data

Keywords: B stars; chemical abundances; non-ETL analysis

Advisor: Simone Daflon

Abstract: The open cluster NGC3293 is part of the Carina complex, which contains several clusters rich with massive stars and the association Car OB1, in addition to nebulae and molecular clouds. The young cluster NGC3293 was widely observed by the Gaia-ESO Survey (GES) with the UVES and GIRAFFE spectrographs coupled to the ESO-Paranal UT2 telescope, with at least 130 stars being of the OBA type. High resolution spectra are reduced and available in the GES collaboration data repository. The objective of this research project is to determine the atmospheric parameters and chemical composition of the OBA stars of the NGC3293 cluster based on non-ETL synthesis, in order to understand their contribution to the chemical evolution of the association Car OB1.

Requirements: graduation in physics or astronomy.

Proto-clusters and the time of reionization

Keywords: Star formation, clusters, reionization, HST, JWST

Advisor: Roderik Overzier

Abstract: The student will study the stage of formation of star clusters. The main objective is to study the formation of the population of young star clusters in the current galaxies and the contribution of proto-star clusters to the process of reionization of the primitive universe. This project is at the interface of stellar astrophysics, extra-galactic and cosmology, and will be co-supervised by Profa. Ana Chies from the Federal University of Rio Grande do Sul.

Requirements: Good understanding of English, experience in programming, curiosity and initiative.