von Boetticher, A, Triaud, AHMJ, Queloz, D, Gill, S, Maxted, PFL, Almleaky, Y, Anderson, DR, Bouchy, F, Burdanov, A, Cameron, AC, Delrez, L, Ducrot, E, Faedi, F, Gillon, M, Maqueo Chew, YG, Hebb, L, Hellier, C, Jehin, E, Lendl, M, Marmier, M, Martin, DV, McCormac, J, Pepe, F, Pollacco, D, Segransan, D, Smalley, B, Thompson, S, Turner, O, Udry, S, Van Grootel, V and West, R (2019) The EBLM Project V. Physical properties of ten fully convective, very-low-mass stars. Astronomy & Astrophysics, 625. ISSN 0004-6361

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Measurements of the physical properties of stars at the lower end of the main sequence are scarce. In this context we report masses, radii and surface gravities of ten very-low-mass stars in eclipsing binary systems, with orbital periods of the order of several days. The objects probe the stellar mass-radius relation in the fully convective regime, M⋆ ≲ 0.35 M⊙, down to the hydrogen burning mass-limit, MHB ∼ 0.07 M⊙. The stars were detected by the WASP survey for transiting extra-solar planets, as low-mass, eclipsing companions orbiting more massive, F- and G-type host stars. We use eclipse observations of the host stars, performed with the TRAPPIST, Leonhard Euler and SPECULOOS telescopes, and radial velocities of the host stars obtained with the CORALIE spectrograph, to determine the physical properties of the low-mass companions. Surface gravities of the low-mass companions are derived from the eclipse and orbital parameters of each system. Spectroscopic measurements of the host star effective temperature and metallicity are used to infer the host star mass and age from stellar evolution models for solar-type stars. Masses and radii of the low-mass companions are then derived from the eclipse and orbital parameters of the binary systems. The objects are compared to stellar evolution models for low-mass stars, to test for an effect of the stellar metallicity and orbital period on the radius of low-mass stars in close binary systems. Measurements are found to be in good agreement with stellar evolution models; a systematic inflation of the radius of low-mass stars with respect to model predictions is limited to 1.6 ± 1.2%, in the fully convective low-mass regime. The sample of ten objects indicates a scaling of the radius of low-mass stars with the host star metallicity. No correlation between stellar radii and the orbital periods of the binary systems is determined. A combined analysis with thirteen comparable objects from the literature is consistent with this result.

Item Type: Article
Additional Information: This is the final published version of the article (version of record). It first appeared online via EDP Sciences at https://doi.org/10.1051/0004-6361/20183 - please refer to any applicable terms of use of the publisher.
Uncontrolled Keywords: stars, low-mass, binaries, eclipsing, spectroscopic, techniques, photometric
Subjects: Q Science > QB Astronomy > QB799 Stars
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
Related URLs:
Depositing User: Symplectic
Date Deposited: 24 Jun 2019 11:23
Last Modified: 24 Jun 2019 11:24
URI: https://eprints.keele.ac.uk/id/eprint/6526

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