Dissertation Defense
Student: Lorenza Fernandes Barraza
Program: Astronomy
Title: “Search for Photometric Periodicities in Hot Subdwarf Stars”
Advisor: Prof. Dr. Marcos Perez Diaz - IAG/USP
Judging Comitee:
- Prof. Dr. Marcos Perez Diaz - Orientador e Presidente) - IAG/USP
- Prof. Dr. Reinaldo Santos de Lima - IAG/USP
- Dr. Marcelo Borges Fernandes – ON (online)
- Prof. Dr. Ronaldo Savarino Levenhagen – UNIFESP
Resumo: The present study addresses the stellar evolution of hot subdwarf stars, specifically
subdwarfs of types B and O. The research focused on the search for periodic
physical phenomena, such as pulsations and, above all, signatures of binary
systems, based on the analysis of a sample of 1378 light curves collected by the
TESS space telescope, corresponding to 563 hot subdwarf stars. To determine the
periods associated with the periodic modulations of these curves, Fourier analysis
was applied using the Lomb-Scargle method. The objects were classified based on
their variabilities into three categories: the eclipsing binary curves, the curves with
sinusoidal or quasi-sinusoidal modulations, and the curves with other modulations.
Finally, the study conducted a statistical analysis of the final sample in order to
estimate the probability of a hot subdwarf, from the studied sample, belonging to a
binary system.
Keywords: Hot subdwarf stars, photometry, light curves, periodicity