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M-dwarf eclipsing binaries in the WFCAM Transit Survey: a study of the mass-radius relationship and of the radius anomaly of low-mass stars

Grant number: 15/18496-8
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): December 01, 2015
Effective date (End): March 31, 2018
Field of knowledge:Physical Sciences and Mathematics - Astronomy - Stellar Astrophysics
Principal researcher:Marcos Perez Diaz
Grantee:Patricia Cardoso Cruz
Home Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil


The characterization of low-mass binary stars, by the determination of their physical and orbital parameters, allows the study of the first stages of evolution of binary systems, and the formation of Cataclysmic Variables. The M-dwarf eclipsing binaries (MEBs) give the most precise ways to measure their fundamental properties, when photometric and spectroscopic data are combined. Nevertheless, only a few MEB systems were well characterized until now and the available data present considerable divergence when compared to stellar models. The radii of the M-dwarfs measured so far are from 5 to 10% greater than the expected values derived from spectral models. Such effect is known as the radius anomaly of low-mass stars. Recently, 16 new low-mass eclipsing binaries were discovered by the WFCAM Transit Survey (WTS), however, only three of them were fully characterized. Every new MEB found is significantly important, given that there are only a few systems known. Therefore, new spectroscopic data were already acquired with the objective to characterize five new MEBs discovered in the WTS. In addition to the determination of the physical and orbital parameters of these systems, an analysis of the relation between mass, radius and orbital period of these objects will be performed in order to investigate the mass-radius relationship by comparing the obtained radii of both components of each system studied with values derived from models of stellar evolution.

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)
GARRIDO, HERNAN E.; CRUZ, PATRICIA; DIAZ, MARCOS P.; AGUILAR, JOHN F. The radius inflation problem in short-period low-mass binaries: a large sample analysis. Monthly Notices of the Royal Astronomical Society, v. 482, n. 4, p. 5379-5388, FEB 2019. Web of Science Citations: 1.
CRUZ, PATRICIA; DIAZ, MARCOS; BIRKBY, JAYNE; BARRADO, DAVID; SIPOCZ, BRIGITTA; HODGKIN, SIMON. Low-mass eclipsing binaries in the WFCAM Transit Survey: the persistence of the M-dwarf radius inflation problem. Monthly Notices of the Royal Astronomical Society, v. 476, n. 4, p. 5253-5267, JUN 2018. Web of Science Citations: 9.

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