A Second Planet Transiting LTT 1445A and a Determination of the Masses of Both Worlds

• Autores: Winters, Jennifer G.; Cloutier, Ryan; Medina, Amber A.; Irwin, Jonathan M.; Charbonneau, David; Astudillo Defru, Nicola; Bonfils, Xavier; Howard, Andrew W.; Isaacson, Howard; Bean, Jacob L.; Seifahrt, Andreas; Teske, Johanna K.; Eastman, Jason D.; Twicken, Joseph D.; Collins, Karen A.; Jensen, Eric L. N.; Quinn, Samuel N.; Payne, Matthew J.; Kristiansen, Martti H.; Spencer, Alton; Vanderburg, Andrew; Zechmeister, Mathias; Weiss, Lauren M.; Wang, Sharon Xuesong; Diaz, Rodrigo Fernando; Brady, Madison; Behmard, Aida; Beard, Corey; Batalha, Natalie M.; Almenara, Jose Manuel
• Año de publicación: 2022
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Exoplanets; Solar neighborhood; Multiple stars; M dwarf stars; Astrophysics - Earth and Planetary Astrophysics; Astrophysics - Solar and Stellar Astrophysics
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

LTT 1445 is a hierarchical triple M-dwarf star system located at a distance of 6.86 pc. The primary star LTT 1445A (0.257 M ⊙) is known to host the transiting planet LTT 1445Ab with an orbital period of 5.36 days, making it the second-closest known transiting exoplanet system, and the closest one for which the host is an M dwarf. Using Transiting Exoplanet Survey Satellite data, we present the discovery of a second planet in the LTT 1445 system, with an orbital period of 3.12 days. We combine radial-velocity measurements obtained from the five spectrographs, Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, High Accuracy Radial Velocity Planet Searcher, High-Resolution Echelle Spectrometer, MAROON-X, and Planet Finder Spectrograph to establish that the new world also orbits LTT 1445A. We determine the mass and radius of LTT 1445Ab to be 2.87 ± 0.25 M ⊕ and 1.304-0.060+0.067 R ⊕, consistent with an Earth-like composition. For the newly discovered LTT 1445Ac, we measure a mass of 1.54-0.19+0.20 M ⊕ and a minimum radius of 1.15 R ⊕, but we cannot determine the radius directly as the signal-to-noise ratio of our light curve permits both grazing and nongrazing configurations. Using MEarth photometry and ground-based spectroscopy, we establish that star C (0.161 M ⊙) is likely the source of the 1.4 day rotation period, and star B (0.215 M ⊙) has a likely rotation period of 6.7 days. We estimate a probable rotation period of 85 days for LTT 1445A. Thus, this triple M-dwarf system appears to be in a special evolutionary stage where the most massive M dwarf has spun down, the intermediate mass M dwarf is in the process of spinning down, while the least massive stellar component has not yet begun to spin down.
Fil: Winters, Jennifer G.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos
Fil: Cloutier, Ryan. Harvard-Smithsonian Center for Astrophysics; Estados Unidos
Fil: Medina, Amber A.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos
Fil: Irwin, Jonathan M.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos
Fil: Charbonneau, David. Harvard-Smithsonian Center for Astrophysics; Estados Unidos
Fil: Astudillo Defru, Nicola. Universidad Católica de la Santísima Concepción; Chile
Fil: Bonfils, Xavier. Universite Grenoble Alpes; Francia
Fil: Howard, Andrew W.. California Institute of Technology; Estados Unidos
Fil: Isaacson, Howard. University of California at Berkeley; Estados Unidos. The University of Queensland; Australia
Fil: Bean, Jacob L.. University of Chicago; Estados Unidos
Fil: Seifahrt, Andreas. University of Chicago; Estados Unidos
Fil: Teske, Johanna K.. University of Carnegie Mellon; Estados Unidos
Fil: Eastman, Jason D.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos
Fil: Twicken, Joseph D.. National Aeronautics and Space Administration; Estados Unidos
Fil: Collins, Karen A.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos
Fil: Jensen, Eric L. N.. Swarthmore College; Estados Unidos
Fil: Quinn, Samuel N.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos
Fil: Payne, Matthew J.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos
Fil: Kristiansen, Martti H.. Brorfelde Observatory; Dinamarca. Technical University of Denmark; Dinamarca
Fil: Spencer, Alton. Western Connecticut State University; Estados Unidos
Fil: Vanderburg, Andrew. Mit Kavli Institute For Astrophysics And Space Research; Estados Unidos
Fil: Zechmeister, Mathias. Universität Göttingen; Alemania
Fil: Weiss, Lauren M.. University of Notre Dame; Estados Unidos
Fil: Wang, Sharon Xuesong. Tsinghua University; China
Fil: Diaz, Rodrigo Fernando. Vanderbilt University; Estados Unidos. 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: Brady, Madison. University of Chicago; Estados Unidos
Fil: Behmard, Aida. California Institute of Technology; Estados Unidos
Fil: Beard, Corey. University of California at Irvine; Estados Unidos
Fil: Batalha, Natalie M.. University of California; Estados Unidos
Fil: Almenara, Jose Manuel. Universite Grenoble Alpes; Francia. Centre National de la Recherche Scientifique; Francia