Dissertation defense
Studant: Nícolas Dick Vidal de Oliveira
Program: Astronomy
Title: "Spectroscopic characterization of the host star of the planetary system PDS 70b,c"
Advisor: Nícolas Dick Vidal de Oliveira
Judging Committee
- Profa. Dra. Jane Cristina Gregorio Hetem – IAG/USP
- Prof. Dr. Jacques Raymond Daniel Lépine - IAG/USP
- Profa. Dra. Silvia Helena Paixão Alencar – UFMG (por videoconferência)
- Dr. José Nacizo Holanda Júnior – ON (por videoconferência)
Abstract:
This work presents a detailed spectroscopic analysis of the T Tauri star PDS 70, focusing on the determination of its atmospheric parameters and the characterization of its lithium abundance. Using high-resolution data obtained with the HARPS spectrograph, line ratio methods and spectral synthesis were applied to estimate the effective temperature, surface gravity, metallicity, and projected rotational velocity of the star. The lithium abundance was determined through spectral synthesis in the region of the 6707.8 Å line. The results indicate an effective temperature of 4176 ± 15 K, a surface gravity of log g = 3.62 ± 0.05, a metallicity of [Fe/H] = −0.11 ± 0.02, and a projected rotational velocity of 16.49 ± 0.04 km s−1 . The lithium abundance (A(Li) = 3.18 ± 0.59) confirms the youth of PDS 70 and is consistent with previous studies of T Tauri stars with similar mass and age. These results reinforce the classification of PDS 70 as a pre-main sequence star, highlighting its importance as a natural laboratory for the study of star and planet formation. The consistency of the obtained values with the literature validates the applied methodologies and contributes to the understanding of the physical processes governing the evolution of young stars and their planetary systems.
Keywords: PDS 70, spectroscopy, atmospheric parameters, Lithium.