Characterization of the L 98-59 multi-planetary system with HARPS: Two confirmed terrestrial planets and a mass upper limit on the third

• Autores: Cloutier, R.; Astudillo Defru, N.; Bonfils, X.; Jenkins, J. S.; Berdiñas, Z.; Ricker, G.; Vanderspek, R.; Latham, D. W.; Seager, S.; Winn, J.; Jenkins, J. M.; Almenara, J. M.; Bouchy, F.; Delfosse, X.; Díaz, M. R.; Diaz, Rodrigo Fernando; Doyon, R.; Figueira, P.; Forveille, T.; Kurtovic, N. T.; Lovis, C.; Mayor, M.; Menou, K.; Morgan, E.; Morris, R.; Muirhead, P.; Murgas, F.; Pepe, F.; Santos, N. C.; Ségransan, D.; Smith, J. C.; Tenenbaum, P.; Torres, G.; Udry, S.; Vezie, M.; Villasenor, J.
• Año de publicación: 2019
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: PLANETARY SYSTEMS; PLANETS AND SATELLITES: TERRESTRIAL PLANETS; STARS: INDIVIDUAL: L 98-59; STARS: LOW-MASS; TECHNIQUES: RADIAL VELOCITIES
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Aims. L 98-59 (TIC 307210830, TOI-175) is a nearby M3 dwarf around which TESS revealed three small transiting planets (0.80, 1.35, 1.57 Earth radii) in a compact configuration with orbital periods shorter than 7.5 days. Here we aim to measure the masses of the known transiting planets in this system using precise radial velocity (RV) measurements taken with the HARPS spectrograph. Methods. We considered both trained and untrained Gaussian process regression models of stellar activity, which are modeled simultaneously with the planetary signals. Our RV analysis was then supplemented with dynamical simulations to provide strong constraints on the planets' orbital eccentricities by requiring long-term stability. Results. We measure the planet masses of the two outermost planets to be 2.42 ± 0.35 and 2.31 ± 0.46 Earth masses, which confirms the bulk terrestrial composition of the former and eludes to a significant radius fraction in an extended gaseous envelope for the latter. We are able to place an upper limit on the mass of the smallest, innermost planet of <1.01 Earth masses with 95% confidence. Our RV plus dynamical stability analysis places strong constraints on the orbital eccentricities and reveals that each planet's orbit likely has e < 0.1. Conclusions. L 98-59 is likely a compact system of two rocky planets plus a third outer planet with a lower bulk density possibly indicative of the planet having retained a modest atmosphere. The system offers a unique laboratory for studies of planet formation, dynamical stability, and comparative atmospheric planetology as the two outer planets are attractive targets for atmospheric characterization through transmission spectroscopy. Continued RV monitoring will help refine the characterization of the innermost planet and potentially reveal additional planets in the system at wider separations.
Fil: Cloutier, R.. University of Toronto; Canadá
Fil: Astudillo Defru, N.. Universidad Católica de la Santísima Concepción; Chile
Fil: Bonfils, X.. Universite Grenoble Alpes; Francia
Fil: Jenkins, J. S.. Universidad de Chile; Chile
Fil: Berdiñas, Z.. Universidad de Chile; Chile
Fil: Ricker, G.. Mit Kavli Institute For Astrophysics And Space Research; Estados Unidos
Fil: Vanderspek, R.. Mit Kavli Institute For Astrophysics And Space Research; Estados Unidos
Fil: Latham, D. W.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos
Fil: Seager, S.. Massachusetts Institute of Technology; Estados Unidos
Fil: Winn, J.. University of Princeton; Estados Unidos
Fil: Jenkins, J. M.. National Aeronautics and Space Administration; Estados Unidos
Fil: Almenara, J. M.. Universite Grenoble Alpes; Francia
Fil: Bouchy, F.. Observatoire Astronomique de L'université de Genve; Suiza
Fil: Delfosse, X.. Universite Grenoble Alpes; Francia
Fil: Díaz, M. R.. Universidad de Chile; Chile
Fil: Diaz, Rodrigo Fernando. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina
Fil: Doyon, R.. University of Montreal; Canadá
Fil: Figueira, P.. No especifíca;
Fil: Forveille, T.. Universite Grenoble Alpes; Francia
Fil: Kurtovic, N. T.. Universidad de Chile; Chile
Fil: Lovis, C.. Observatoire Astronomique de L'université de Genve; Suiza
Fil: Mayor, M.. Observatoire Astronomique de L'université de Genve; Suiza
Fil: Menou, K.. University of Toronto; Canadá
Fil: Morgan, E.. Mit Kavli Institute For Astrophysics And Space Research; Estados Unidos
Fil: Morris, R.. No especifíca;
Fil: Muirhead, P.. Boston University; Estados Unidos
Fil: Murgas, F.. Universite Grenoble Alpes; Francia
Fil: Pepe, F.. Observatoire Astronomique de L'université de Genve; Suiza
Fil: Santos, N. C.. Universidad de Porto; Portugal
Fil: Ségransan, D.. Observatoire Astronomique de L'université de Genve; Suiza
Fil: Smith, J. C.. No especifíca;
Fil: Tenenbaum, P.. No especifíca;
Fil: Torres, G.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos
Fil: Udry, S.. Observatoire Astronomique de L'université de Genve; Suiza
Fil: Vezie, M.. Mit Kavli Institute For Astrophysics And Space Research; Estados Unidos
Fil: Villasenor, J.. Mit Kavli Institute For Astrophysics And Space Research; Estados Unidos