The CARMENES search for exoplanets around M dwarfs. Two temperate Earth-mass planet candidates around Teegarden's Star
Schmitt, J. H. M. M.; Rebolo, R.; del Burgo, C.; Stahl, O.; Alonso-Floriano, F. J.; Sánchez-López, A.; López-Puertas, M.; Nagel, E.; Amado, P. J.; Bauer, F. F.; Caballero, J. A.; Czesla, S.; Nortmann, L.; Pallé, E.; Reiners, A.; Ribas, I.; Quirrenbach, A.; Aceituno, J.; Anglada-Escudé, G.; Béjar, V. J. S.; Henning, T.; Kaminski, A.; Kürster, M.; Lampón, M.; Lara, L. M.; Montes, D.; Morales, J. C.; Tal-Or, L.; Zapatero Osorio, M. R.; Zechmeister, M.; Passegger, V. M.; Schweitzer, A.; Shulyak, D.; Hauschildt, P. H.; Cortés-Contreras, M.; Azzaro, M.; Dreizler, S.; Jeffers, S. V.; Lafarga, M.; Martín, E. L.; Hatzes, A. P.; Narita, N.; Nowak, G.; Rodríguez, E.; Martín-Ruiz, S.; Suárez, J. C.; Rix, H. -W.; Lalitha, S.; Solano, E.; Perryman, M. A. C.; Mall, U.; Casasayas-Barris, N.; Galadí-Enríquez, D.; Sanz-Forcada, J.; Barrado, D.; Luque, R.; Rodler, F.; Oshagh, M.; González Hernández, J. I.; Yan, F.; Seifert, W.; Casanova, V.; Mancini, L.; Claret, A.; Fukui, A.; Parviainen, H.; Lodieu, N.; Stock, S.; Herrero, E.; Kemmer, J.; Reffert, S.; Cifuentes, C.; Tabernero, H. M.; Guijarro, A.; Dorda, R.; Kim, M.; Gesa, L.; Wagner, K.; Perger, M.; Rosich, A.; Fernández, M.; Launhardt, R.; Kossakowski, D.; Bluhm, P.; Chaturvedi, P.; Pavlov, A.; Rodríguez López, C.; Schöfer, P.; Trifonov, T.; Mandel, H.; Ofir, A.; Sota, A.; González-Álvarez, E.; Klein, R.; Berdiñas, Z. M.; González-Cuesta, L.; López-González, M. J.; Pedraz, S.; Marfil, E.; Bergond, G.; Fernández-Martín, A.; Hermelo, I.; Vico Linares, J. I.; Sarkis, P.; Fuhrmeister, B.; López-Santiago, J.; Klutsch, A.; Stürmer, J.; Aceituno, F. J.; Klüter, J.; Xu, W.; García Vargas, M. L.; Pérez-Calpena, A.; Abril, M.; Ammler-von Eiff, M.; Antona Jiménez, R.; Anwand-Heerwart, H.; Arroyo-Torres, B.; Baroch, D.; Becerril, S.; Benítez, D.; Brinkmöller, M.; Calvo Ortega, R.; Cano, J.; Cardona Guillén, C.; Carro, J.; Cárdenas Vázquez, M. C.; Casal, E.; Colomé, J.; Díez-Alonso, E.; Gallardo Cava, I.; Garcia de la Fuente, J.; Garcia-Piquer, A.; Góngora Rueda, J.; González-Peinado, R.; Grözinger, U.; Guàrdia, J.; de Guindos, E.; Hedrosa, R. P.; Helmling, J.; Hernández Arabi, R.; Hernández Castaño, L.; Hernández Otero, F.; Hintz, D.; Huke, P.; Huber, A.; Johnson, E. N.; de Juan, E.; Klahr, H.; Labarga, F.; Llamas, M.; Lázaro, F. J.; López del Fresno, M.; López Salas, J. F.; Magán Madinabeitia, H.; Marín Molina, J. A.; Maroto Fernández, D.; Martín-Fernández, P.; Marvin, C. J.; Mirabet, E.; Montañés-Rodríguez, P.; Moreno-Raya, M. E.; Naranjo, V.; Panduro, J.; Pascual, J.; Pérez Medialdea, D.; Rabaza, O.; Ramón Ballesta, A.; Redondo, P.; Reinhardt, S.; Rhode, P.; Rodríguez Trinidad, A.; Sadegi, S.; Sánchez-Blanco, E.; Sánchez Carrasco, M. A.; Sarmiento, L. F.; Schäfer, S.; Strachan, J. B. P.; Stuber, T.; Tala Pinto, M.; Veredas, G.; Vilardell, F.; Wolthoff, V.
Germany, Spain, Israel, United Kingdom, Netherlands, Chile, Mexico, Japan, Italy, Ireland, United States
Abstract
Context. Teegarden's Star is the brightest and one of the nearest ultra-cool dwarfs in the solar neighbourhood. For its late spectral type (M7.0 V), the star shows relatively little activity and is a prime target for near-infrared radial velocity surveys such as CARMENES.
Aims: As part of the CARMENES search for exoplanets around M dwarfs, we obtained more than 200 radial-velocity measurements of Teegarden's Star and analysed them for planetary signals.
Methods: We find periodic variability in the radial velocities of Teegarden's Star. We also studied photometric measurements to rule out stellar brightness variations mimicking planetary signals.
Results: We find evidence for two planet candidates, each with 1.1 M⊕ minimum mass, orbiting at periods of 4.91 and 11.4 d, respectively. No evidence for planetary transits could be found in archival and follow-up photometry. Small photometric variability is suggestive of slow rotation and old age.
Conclusions: The two planets are among the lowest-mass planets discovered so far, and they are the first Earth-mass planets around an ultra-cool dwarf for which the masses have been determined using radial velocities.