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Analysis of stellar activity signals in solar-type stars using Gaussian Processes

Grant number: 23/16319-8
Support Opportunities:Scholarships abroad - Research Internship - Doctorate (Direct)
Start date: July 08, 2024
End date: July 07, 2025
Field of knowledge:Physical Sciences and Mathematics - Astronomy - Stellar Astrophysics
Principal Investigator:Jorge Luis Melendez Moreno
Grantee:Gabriela Carvalho Silva
Supervisor: Raphaelle Haywood
Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Institution abroad: University of Exeter, Exeter, England  
Associated to the scholarship:21/01303-3 - Modeling spectroscopic signatures of stellar activity, BP.DD

Abstract

The stellar magnetic activity and rotation are highly dependent on each other. The mechanism behind the magnetic field generation is related to rotation, as described by the dynamo theory. At the same time, the rotation rate reflects the angular momentum of the star, which changes with activity levels. So far, our knowledge is limited for older stars, because it is harder to detect rotation rates in slow and less active stars. On the other hand, our understanding of the stellar magnetic activity is also limited particularly because activity cycles are not strictly periodic, but have a quasi-periodic nature. It is crucial to discern modulations of stellar signals from different phenomena, not only for fundamental stellar astrophysics studies, but also to avoid spurious exoplanet detections, as activity signals are known to mimic planet-induced modulations.This BEPE project aims to explore the application of Gaussian Processes (GP) to analyze stellar rotation and magnetic activity in solar-type stars. We will study rotational and activity-induced modulations through time-series of different activity proxies derived from high precision spectrographs. We will take advantage of the precise estimated ages of the solar twins to address the evolution of rotation and activity with stellar age. The BEPE internship will allow to acquire expertise in the advanced GP method. This will bring a valuable cutting-edge technique that could be implemented in our group in Brazil.

News published in Agência FAPESP Newsletter about the scholarship:
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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
CARVALHO-SILVA, GABRIELA; MELENDEZ, JORGE; RATHSAM, ANNE; SHEJEELAMMAL, J.; MARTOS, GIULIA; LORENZO-OLIVEIRA, DIEGO; SPINA, LORENZO; RIBEIRO ALVES, DEBORA. A New Age-Activity Relation For Solar Analogs that Accounts for Metallicity. Astrophysical Journal Letters, v. 983, n. 2, p. 7-pg., . (23/16319-8, 21/01303-3, 22/05833-0, 22/10325-3, 18/04055-8)