Dissertation Defense
Student: Vitória Bellecerie da Fonseca
Program: Astronomy
Title: "Exoplanets of Red Dwarf Stars: Transits and Habitability"
Advisor: Prof. Dr. Eduardo Janot Pacheco - IAG/USP
Judging Committee:
- Prof. Dr. Eduardo Janot Pacheco - Orientador e Presidente - IAG/USP (on videconference)
- Prof. Dr. Amâncio Cesar Santos Friaça - IAG/USP
- Prof. Dr. Marcelo Emilio – UEPG
- Dr. Eder Martioli – LNA/MCTI
Abstract:
The question of the existence of life beyond Earth has driven astrophysical research, with the search of extraterrestrial life focusing on the thousands of exoplanets discovered orbiting stars outside the Solar System. The habitable Zone (HZ) is a key concept that indicates the orbital area in which the temperature could permit liquid water on the surface of a planet with atmosphere, accounting for inner and outer edges of 100 and 0 °C, respectively. Although the HZ definition is biased towards our knowledge about the Earth, the true limits for cosmic life are unknown, making the characterization of exoplanets, in terms of their interiors, surfaces, and atmospheres, a fundamental step. Detecting transits using differential photometry is an effective technique for identifying and characterizing these worlds, allowing for the estimation of parameters such as the planetary radius relative to the star and the orbital period. In 2024 and 2025, we observed planetary transits at the Observatório do Pico dos Dias (OPD/LNA) with the 1.6m Perkin-Elmer f/10 telescope and the SPARC4 instrument (griz bands - SDSS). The targets were selected via ExoClock, with priority given to terrestrial planets of red dwarf stars (types K and M), relevant for the search for potential habitable exoplanets, for instance L 98-59d and GJ 1132b. Gas giants, such as Qatar-2b, were also observed to improve time management at the telescope. The transits are being studied with the BATMAN and ECLIPSE codes. We obtained and compared with the literature the time of the transit, the planetary radius relative to the star, and the orbital inclination. Additionally, we estimated the latitude, longitude, radius, and temperature of a spot on the star Qatar-2. Such results are crucial for the accurate characterization of exoplanets and contributions to the knowledge base on planetary populations, providing support for future investigations into habitability.
Keywords: Planetary Systems, Stars and Solar Physics, Astrobiology