Examinando por Autor "Dreizler, S."

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Acceso Abierto
A giant exoplanet orbiting a very-low-mass star challenges planet formation models
(American Association for the Advancement of Science, 2019-09-27) Morales, J. C.; Mustill, A. J.; Ribas, I.; Davies, M. B.; Reiners, A.; Bauer, F. F.; Kossakowski, D.; Herrero, E.; Rodríguez, E.; López González, M. J.; Rodríguez López, C.; Cifuentes, C.; Mordasini, C.; Jeffers, S. V.; Rix, H. W.; Ofir, A.; Kürster, M.; Henning, T.; Emsenhuber, A.; Passegger, V. M.; Abellán, F. J.; Rodríguez Trinidad, A.; Pedraz, S.; Aceituno, J.; Seifert, W.; Fernández Martín, A.; Zechmeister, M.; De Juan, E.; Perryman, M. A. C.; Antona, R.; Alonso Floriano, F. J.; Ferro, I. M.; Johnson, E. N.; Labiche, N.; Rebolo, R.; Becerril Jarque, S.; Azzaro, M.; Fuhrmeister, B.; Lizon, J. L.; Perger, M.; Brinkmöller, M.; Berdiñas, Z. M.; Galadí Enríquez, D.; López Santiago, J.; Cortés Contreras, M.; Calvo Ortega, R.; Del Burgo, C.; Gallardo Cava, I.; Rosich, A.; Cardona Guillén, C.; Cano, J.; García Vargas, M. L.; Amado, P. J.; Casanova, V.; Carro, J.; García Piquer, A.; Kaminski, A.; Chaturvedi, P.; Gesa, L.; Abril, M.; Claret, A.; González Álvarez, E.; Ammler von Eiff, M.; Czesla, S.; Barrado, D.; Dorda, R.; González Peinado, R.; Fernández Hernández, Maite; Klüter, J.; Kim, M.; Lara, L. M.; Lampón, M.; López del Fresno, M.; Lodieu, N.; Mancini, L.; Mall, U.; Martín Fernández, P.; Mirabet, E.; Nortmann, L.; Pallé, E.; Caballero, J. A.; Huke, P.; Huber, A.; Holgado, G.; Klutsch, A.; Launhardt, R.; López Salas, F. J.; Stürmer, J.; Suárez, J. C.; Tabernero, H.; Tulloch, S. M.; Veredas, G.; Vico Linares, J. I.; Vilardell, F.; Wagner, K.; Winkler, J.; Wolthoff, V.; Sánchez López, A.; Sánchez Blanco, E.; Sadegi, S.; Labarga, F.; Marfil, E.; Casasayas Barris, N.; Bergond, G.; Martín, E. L.; Mandel, H.; Sarkis, P.; Lázaro, F. J.; Luque, R.; Burn, R.; Marvin, E. L.; Martín Ruiz, S.; Sarmiento, L. F.; González Cuesta, L.; Anglada Escudé, G.; Cárdenas, M. C.; Nelson, R. P.; Moya, A.; Schäfer, S.; Reffert, S.; Casal, E.; Pascual, J.; Nowak, G.; Schlecker, M.; Quirrenbach, A.; Kemmer, J.; Pérez Medialdea, D.; Pavlov, A.; Schmitt, J. H. M. M.; Lalitha, S.; Rabaza, O.; Pérez Calpena, A.; Schöfer, P.; Llamas, M.; Redondo, P.; Ramón Ballesta, A.; Magán Madinabeitia, H.; Rodler, F.; Sota, A.; Marín Molina, J. A.; Sabotta, S.; Stahl, O.; Martínez Rodríguez, H.; Salz, M.; Stock, S.; Naranjo, V.; Sánchez Carrasco, M. A.; Stuber, T.; Sanz Forcada, J.; Johansen, A.; Baroch, D.; Lafarga, M.; Dreizler, S.; Tal Or, L.; Schweitzer, A.; Hagen, H. J.; Guenther, E. W.; Montes, D.; Aceituno, Francisco José; Arroyo Torres, B.; Benítez, D.; Kehr, M.; Béjar, V. J. S.; Zapatero Osorio, M. R.; Yan, F.; Klahr, H.; Nagel, E.; Trifonov, T.; Guàrdia, J.; Guijarro, A.; De Guindos, E.; Hatzes, A. P.; Hauschildt, P. H.; Hedrosa, R. P.; Hermelo, I.; Hernández Arabi, R.; Hernández Otero, F.; Hintz, D.; Díez Alonso, E.; Colomé, J.; González Hernández, Carmen; Solano, Enrique; Israel Science Foundation (ISF); Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT); Swiss National Science Foundation (SNSF); Deutsches Zentrum für Luft- und Raumfahrt (DLR); Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR); European Research Council (ERC); Generalitat de Catalunya; Deutsche Forschungsgemeinschaft (DFG); Queen Mary University of London; Consejo Nacional de Ciencia y Tecnología (CONACYT); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Morales, J. C. [0000-0003-0061-518X]; Mustill, A. J. [0000-0002-2086-3642]; Ribas, I. [0000-0002-6689-0312]; Davies, M. B. [0000-0001-6080-1190]; Bauer, F. F. [0000-0003-1212-5225]; Herrrero, E. [0000-0001-8602-6639]; Rodríguez, E. [0000-0001-6827-9077]; López González, M. J. [0000-0001-8104-5128]; Rodríguez López, C. [0000-0001-5559-7850]; López González, M. J. [0000-0001-8104-5128]; Rodríguez López, C. [0000-0001-5559-7850]; Luque, R. [0000-0002-4671-2957]; López Santiago, J. [0000-0003-2402-8166]; Perger, M. [0000-0001-7098-0372]; Guenther, E. W. [0000-0002-9130-6747]; Schmitt, J. H. M. M. [0000-0003-2554-9916]; Mordasini, C. [0000-0002-1013-2811]; Aceituno, J. [0000-0003-0487-1105]; Stock, S. [0000-0002-1166-9338]; Lafarga, M. [0000-0002-8815-9416]; Nagel, E. [0000-0002-4019-3631]; Barrado, D. [0000-0002-5971-9242]; Tulloch, S. [0000-0003-0840-8521]; Rosich, A. [0000-0002-9141-3067]; Trifonov, T. [0000-0002-0236-775X]; Bergond, G. [0000-0003-3132-9215]; Zapatero Osorio, M. R. [0000-0001-5664-2852]; Kaminski, A. [0000-0003-0203-8208]; Montes, D. [0000-0002-7779-238X]; Cano, J. [0000-0003-1984-5401]; Baroch, D. [0000-0001-7568-5161]; Alonso Floriano, F. J. [0000-0003-1202-5734]; Sabotta, S. [0000-0001-9078-5574]; Ammler-von Eiff, M. [0000-0001-9565-1698]; Chaturvedi, P. [0000-0002-1887-1192]; Anglada Escudé, G. [0000-0002-3645-5977]; Becerril Jarque, S. [0000-0001-9009-1150]; Díez Alonso, E. [0000-0002-5826-9892]; Passegger, V. M. [0000-0002-8569-7243]; Burn, R. [0000-0002-9020-7309]; García Vargas, M. L. [0000-0002-2058-3528]; Amado, P. J. [0000-0002-8388-6040]; Cardona Guillén, C. [0000-0002-2198-4200]; Carro, J. [0000-0002-0838-3603]; Guàrdia, J. [0000-0002-7191-9001]; Abellán, F. J. [0000-0002-5724-1636]; Cifuentes, C. [0000-0003-1715-5087]; Colomé, J. [0000-0002-1678-2241]; Hermelo, I. [0000-0001-9178-694X]; Arroyo Torres, B. [0000-0002-3392-4694]; Emsenhuber, A. [0000-0002-8811-1914]; Fuhrmeister, B. [0000-0001-8321-5514]; Johnson, E. [0000-0003-2260-5134]; Berdiñas, Z. M. [0000-0002-6057-6461]; González Álvarez, E. [0000-0002-4820-2053]; González Cuesta, L. [0000-0002-1241-5508]; González Hernández, J. I. [0000-0002-0264-7356]; Klüter, J. [0000-0002-3469-5133]; Calvo Ortega, R. [0000-0003-3693-6030]; Guijarro, A. [0000-0001-5518-1759]; Lara, L. M. [0000-0002-7184-920X]; Casasayas Barris, N. [0000-0002-2891-8222]; Hintz, D. [0000-0002-5274-2589]; López del Fresno, M. [0000-0002-9479-7780]; Czesla, S. [0000-0002-4203-4773]; De Juan Fernández, E. [0000-0002-9382-4505]; Kehr, M. [0000-0002-7420-7368]; Marín Molina, J. A. [0000-0002-3525-0806]; Galadí Enríquez, D. [0000-0003-4946-5653]; Klutsch, A. [0000-0001-7869-3888]; Labarga, F. [0000-0002-7143-0206]; Martínez Rodríguez, H. [0000-0002-1919-228X]; González Peinado, R. [0000-0002-6658-8930]; Launhardt, R. [0000-0002-8298-2663]; Lizon, J. L. [0000-0001-8928-2566]; Naranjo, V. [0000-0003-0097-1061]; De Guindos, E. [0000-0002-8124-9101]; Magan Madinabeitia, H. [0000-0003-1243-4597]; Aceituno, F. J. [0000-0001-8074-4760]; Manici, L. [0000-0002-9428-8732]; Ofir, A. [0000-0002-9152-5042]; Huke, P. [0000-0001-5913-2743]; Martín, E. [0000-0002-1208-4833]; Rabaza, O. [0000-0003-2766-2103]; Kim, M. [0000-0001-6218-2004]; Marvin, C. J. [0000-0002-2249-2611]; Rodríguez Trinidad, A. [0000-0002-3356-8634]; Lampón, M. [0000-0002-0183-7158]; Nelson, R. [0000-0002-9687-8779]; Nortmann, L. [0000-0001-8419-8760]; Sanz Forcada, J. [0000-0002-1600-7835]; Lodieu, N. [0000-0002-3612-8968]; Pascual Granado, J. [0000-0003-0139-6951]; Pedraz, S. [0000-0003-1346-208X]; Schäfer, S. [0000-0001-8597-8048]; Marfil, E. [0000-0001-8907-4775]; Ramón Ballesta, A. [0000-0002-4323-0610]; Redondo, P. G. [0000-0001-5992-5778]; Schöfer, P. [0000-0002-5969-3708]; Martín Ruiz, S. [0000-0002-9006-7182]; Sadegi, S. [0000-0001-9897-6121]; García Piquer, A. [0000-0002-6872-4262]; Sánchez Carrasco, M. A. [0000-0001-5533-3660]; Stuber, T. [0000-0003-2185-0525]; Moya, A. [0000-0003-1665-5389]; Sarkis, P. [0000-0001-8128-3126]; Vilardell, F. [0000-0003-0441-1504]; Nowak, G. [0000-0002-7031-7754]; Schlecker, M. [0000-0001-8355-2107]; Béjar, V. J. S. [0000-0002-5086-4232]; Pérez Calpena, A. [0000-0001-7361-9240]; Solano, E. [0000-0003-1885-5130]; Sota, A. [https://orcid.org/0000-0002-9404-6952]; Klahr, H. [0000-0002-8227-5467]; Rodler, F. [0000-0003-0650-5723]; Suárez, J. C. [0000-0003-3649-8384]; Tabernero, H. [0000-0002-8087-4298]; Cortés Contreras, M. [0000-0003-3734-9866]; Sánchez López, A. [0000-0002-0516-7956]; Winkler, J. [0000-0003-0568-8820]; Yan, F. [0000-0001-9585-9034]; Reffert, S. [0000-0002-0460-8289]; Sarmiento, L. F. [0000-0002-8475-9705]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709
Surveys have shown that super-Earth and Neptune-mass exoplanets are more frequent than gas giants around low-mass stars, as predicted by the core accretion theory of planet formation. We report the discovery of a giant planet around the very-low-mass star GJ 3512, as determined by optical and near-infrared radial-velocity observations. The planet has a minimum mass of 0.46 Jupiter masses, very high for such a small host star, and an eccentric 204-day orbit. Dynamical models show that the high eccentricity is most likely due to planet-planet interactions. We use simulations to demonstrate that the GJ 3512 planetary system challenges generally accepted formation theories, and that it puts constraints on the planet accretion and migration rates. Disk instabilities may be more efficient in forming planets than previously thought.Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science
Restringido
A nearby transiting rocky exoplanet that is suitable for atmospheric investigation
(Science, 2021-03-05) Trifonov, T.; Caballero, J. A.; Morales, J. C.; Seifahrt, A.; Reiners, A.; Bean, J. L.; Luque, R.; Parviainen, H.; Pallé, E.; Stock, S.; Zechmeister, M.; Amado, P. J.; Anglada Escudé, G.; Azzaro, M.; Barclay, T.; Béjar, V. J. S.; Bluhm, P.; Casasayas Barris, N.; Cifuentes, C.; Collins, K. A.; Collins, K. I.; Cortés Contreras, M.; De Leon, J. P.; Dreizler, S.; Dressing, C. D.; Esparza Borges, E.; Espinoza, N.; Fausnaugh, M.; Fukui, A.; Hatzes, A. P.; Hellier, C.; Henning, T.; Henze, C. E.; Herrero, E.; Jeffers, S. V.; Jenkins, J. M.; Jensen, E. L. N.; Kaminski, A.; Kasper, D.; Kossakowski, D.; Kürster, M.; Lafarga, M.; Latham, D. W.; Mann, A. W.; Molaverdikhani, K.; Montes, D.; Montet, B. T.; Murgas Alcaino, F.; Narita, N.; Oshagh, M.; Passegger, V. M.; Pollacco, D.; Quinn, S. N.; Quirrenbach, A.; Ricker, G. R.; Rodríguez López, C.; Sánz Forcada, J.; Schwarz, R. P.; Schweitzer, A.; Seager, S.; Shporer, A.; Stangret, M.; Stürmer, J.; Tan, T. G.; Tenenbaum, P.; Twicken, J. D.; Vanderspek, R.; Winn, J. N.; Deutsche Forschungsgemeinschaft (DFG); Agencia Estatal de Investigación (AEI); National Aeronautics and Space Administration (NASA); European Research Council (ERC); Japan Society for the Promotion of Science (JSPS); La Caixa; Japan Science and Technology Agency (JST); Trifonov, T. [0000-0002-0236-775X]; Caballero, J. A. [0000-0002-7349-1387]; Morales, J. C. [0000-0003-0061-518X]; Seifahrt, A. [0000-0003-4526-3747]; Ribas, I. [0000-0002-6689-0312]; Bean, J. [0000-0003-4733-6532]; Luque, R. [0000-0002-4671-2957]; Parviainen, H. [0000-0001-5519-1391]; Pallé, E. [0000-0003-0987-1593]; Stock, S. [0000-0002-1166-9338]; Zechmeister, M. [0000-0002-6532-4378]; Amado, P. J. [0000-0002-8388-6040]; Anglada Escudé, G. [0000-0002-3645-5977]; Azzaro, M. [0000-0002-1317-0661]; Barclay, T. [0000-0001-7139-2724]; Béjar, V. J. S. [0000-0002-5086-4232]; Bluhm, P. [0000-0002-0374-8466]; Casasayas Barris, N. [0000-0002-2891-8222]; Cifuentes, C. [0000-0003-1715-5087]; Collins, K. A. [0000-0001-6588-9574]; Collins, K. I. [0000-0003-2781-3207]; Cortés Contreras, M. [0000-0003-3734-9866]; Dreizler, S. [0000-0001-6187-5941]; Dressing, C. D. [0000-0001-8189-0233]; Esparza Borges, E. [0000-0002-2341-3233]; Espinoza, N. [0000-0001-9513-1449]; Fausnaugh, M. [0000-0002-9113-7162]; Fukui, A. [0000-0002-4909-5763]; Hatzes, A. P. [0000-0002-3404-8358]; Hellier, C. [0000-0002-3439-1439]; Henning, T. [0000-0002-1493-300X]; Herrero, E. [0000-0001-8602-6639]; Jeffers, S. V. [0000-0003-2490-4779]; Jenkins, J. M. [0000-0002-4715-9460]; Jensen, E. L. N. [0000-0002-4625-7333]; Kaminski, A. [0000-0003-0203-8208]; Kasper, D. [0000-0003-0534-6388]; Kossakowski, D. [0000-0002-0436-7833]; Lafarga, M. [0000-0002-8815-9416]; Latham, D. W. [0000-0001-9911-7388]; Mann, A. W. [0000-0003-3654-1602]; Molaverdikhani, K. [0000-0002-0502-0428]; Montes, D. [0000-0002-7779-238X]; Montet, B. T. [0000-0001-7516-8308]; Murgas, F. [0000-0001-9087-1245]; Narita, N. [0000-0001-8511-2981]; Oshagh, M. [0000-0002-0715-8789]; Passegger, V. M. [0000-0002-8569-7243]; Pollacco, D. [0000-0001-9850-9697]; Quinn, S. N. [0000-0002-8964-8377]; Rodríguez López, C. [0000-0001-5559-7850]; Sanz Forcada, J. [0000-0002-1600-7835]; Schwarz, R. P. [0000-0001-8227-1020]; Schweitzer, A. [0000-0002-1624-0389]; Seager, S. [0000-0002-6892-6948]; Stangret, M. [0000-0002-1812-8024]; Stürmer, J. [0000-0002-4410-4712]; Tan, T. G. [0000-0001-5603-6895]; Tenenbaum, P. [0000-0002-1949-4720]; Twicken, J. D. [0000-0002-6778-7552]; Vanderspek, R. [0000-0001-6763-6562]; Winn, J. N. [0000-0002-4265-047X]; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Spectroscopy of transiting exoplanets can be used to investigate their atmospheric properties and habitability. Combining radial velocity (RV) and transit data provides additional information on exoplanet physical properties. We detect a transiting rocky planet with an orbital period of 1.467 days around the nearby red dwarf star Gliese 486. The planet Gliese 486 b is 2.81 Earth masses and 1.31 Earth radii, with uncertainties of 5%, as determined from RV data and photometric light curves. The host star is at a distance of ~8.1 parsecs, has a J-band magnitude of ~7.2, and is observable from both hemispheres of Earth. On the basis of these properties and the planet’s short orbital period and high equilibrium temperature, we show that this terrestrial planet is suitable for emission and transit spectroscopy.
Acceso Abierto
Gliese 49: activity evolution and detection of a super-Earth A HADES and CARMENES collaboration
(EDP Sciences, 2019-04-24) Perger, M.; Scandariato, G.; Ribas, I.; Morales, J. C.; Affer, L.; Azzaro, M.; Amado, P. J.; Anglada Escudé, G.; Baroch, D.; Barrado, D.; Bauer, F. F.; Béjar, V. J. S.; Caballero, J. A.; Cortés Contreras, M.; Damasso, M.; Dreizler, S.; González Cuesta, L.; Guenther, E. W.; Henning, T.; Herrero, E.; Jeffers, S. V.; Kaminski, A.; Kürster, M.; Lafarga, M.; Leto, G.; López González, M. J.; Maldonado, J.; Micela, G.; Montes, D.; Pinamonti, M.; Quirrenbach, A.; Rebolo, R.; Reiners, A.; Rodríguez, E.; Rodríguez López, C.; Schimitt, J. H. M. M.; Sozzetti, A.; Suárez Mascareño, A.; Toledo Padrón, B.; Zanmar Sánchez, R.; Zapatero Osorio, M. R.; Zechmeister, M.; González Hernández, Carmen; Ministerio de Economía y Competitividad (MINECO); European Commission (EC); Agencia Estatal de Investigación (AEI); 0000-0001-7098-0372; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. Small planets around low-mass stars often show orbital periods in a range that corresponds to the temperate zones of their host stars which are therefore of prime interest for planet searches. Surface phenomena such as spots and faculae create periodic signals in radial velocities and in observational activity tracers in the same range, so they can mimic or hide true planetary signals. Aims. We aim to detect Doppler signals corresponding to planetary companions, determine their most probable orbital configurations, and understand the stellar activity and its impact on different datasets. Methods. We analyzed 22 yr of data of the M1.5 V-type star Gl 49 (BD+61 195) including HARPS-N and CARMENES spectrographs, complemented by APT2 and SNO photometry. Activity indices are calculated from the observed spectra, and all datasets are analyzed with periodograms and noise models. We investigated how the variation of stellar activity imprints on our datasets. We further tested the origin of the signals and investigate phase shifts between the different sets. To search for the best-fit model we maximize the likelihood function in a Markov chain Monte Carlo approach. Results. As a result of this study, we are able to detect the super-Earth Gl 49b with a minimum mass of 5.6 M⊕. It orbits its host star with a period of 13.85 d at a semi-major axis of 0.090 au and we calculate an equilibrium temperature of 350 K and a transit probability of 2.0%. The contribution from the spot-dominated host star to the different datasets is complex, and includes signals from the stellar rotation at 18.86 d, evolutionary timescales of activity phenomena at 40–80 d, and a long-term variation of at least four years.
Acceso Abierto
Mass and density of the transiting hot and rocky super-Earth LHS 1478 b (TOI-1640 b)
(EDP Sciences, 2021-05-21) Soto, M. G.; Anglada Escudé, G.; Dreizler, S.; Molaverdikhani, K.; Kemmer, J.; Rodríguez López, C.; Lillo Box, J.; Pallé, E.; Espinoza, N.; Caballero, J. A.; Quirrenbach, A.; Ribas, I.; Reiners, A.; Narita, N.; Hirano, T.; Amado, P. J.; Béjar, V. J. S.; Bluhm, P.; Burke, C. J.; Caldwell, D. A.; Charbonneau, D.; Cloutier, R.; Collins, K. A.; Cortés Contreras, M.; Girardin, E.; Guerra, P.; Harakawa, H.; Hatzes, A. P.; Irwin, J.; Jenkins, J. M.; Jensen, E.; Kawauchi, K.; Kotani, T.; Kudo, T.; Kunimoto, M.; Kuzuhara, M.; Latham, D. W.; Montes, D.; Morales, J. C.; Mori, M.; Nelson, R. P.; Omiya, M.; Pedraz, S.; Passegger, V. M.; Rackham, B. V.; Rudat, A.; Schlieder, J. E.; Schöfer, P.; Schweitzer, A.; Selezneva, A.; Stockdale, C.; Tamura, M.; Trifonov, T.; Vanderspek, R.; Watanabe, N.; Deutsche Forschungsgemeinschaft (DFG); Ministerio de Economía y Competitividad (MINECO); Junta de Andalucía; Science and Technology Facilities Council (STFC); National Aeronautics and Space Administration (NASA); Agencia Estatal de Investigación (AEI); Generalitat de Catalunya; Japan Society for the Promotion of Science (JSPS); Soto, M. G. [0000-0001-9743-5649]; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
One of the main objectives of the Transiting Exoplanet Survey Satellite (TESS) mission is the discovery of small rocky planets around relatively bright nearby stars. Here, we report the discovery and characterization of the transiting super-Earth planet orbiting LHS 1478 (TOI-1640). The star is an inactive red dwarf (J ~ 9.6 mag and spectral type m3 V) with mass and radius estimates of 0.20 ± 0.01M⊙ and 0.25 ± 0.01R⊙, respectively, and an effective temperature of 3381 ± 54 K. It was observed by TESS in four sectors. These data revealed a transit-like feature with a period of 1.949 days. We combined the TESS data with three ground-based transit measurements, 57 radial velocity (RV) measurements from CARMENES, and 13 RV measurements from IRD, determining that the signal is produced by a planet with a mass of 2.33−0.20+0.20 M⊕ and a radius of 1.24−0.05+0.05 R⊕. The resulting bulk density of this planet is 6.67 g cm−3, which is consistent with a rocky planet with an Fe- and MgSiO3-dominated composition. Although the planet would be too hot to sustain liquid water on its surface (its equilibrium temperature is about ~595 K, suggesting aVenus-like atmosphere), spectroscopic metrics based on the capabilities of the forthcoming James Webb Space Telescope and the fact that the host star is rather inactive indicate that this is one of the most favorable known rocky exoplanets for atmospheric characterization.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs A deep learning approach to determine fundamental parameters of target stars
(EDP Sciences, 2020-09-30) Passegger, V. M.; Bello García, A.; Ordieres Meré, J.; Caballero, J. A.; Schweitzer, A.; González Marcos, A.; Ribas, I.; Reiners, A.; Quirrenbach, A.; Amado, P. J.; Azzaro, M.; Bauer, F. F.; Béjar, V. J. S.; Cortés Contreras, M.; Dreizler, S.; Hatzes, A. P.; Henning, T.; Jeffers, S. V.; Kaminski, A.; Kürster, M.; Lafarga, M.; Marfil, E.; Montes, D.; Morales, J. C.; Nagel, E.; Sarro, L. M.; Tabernero, H. M.; Zechmeister, M.; Solano, Enrique; Agencia Estatal de Investigación (AEI); Fundacao para a Ciencia e a Tecnologia (FCT); National Aeronautics and Space Administration (NASA); Bello García, A. [0000-0001-8691-3342]; Ordieres Meré, J. [0000-0002-9677-6764]; Caballero, J. A. [0000-0002-7349-1387]; González Marcos, A. [0000-0003-4684-659X]; Ribas, I. [0000-0002-6689-0312]; Azzaro, M. [0000-0002-1317-0661]; Kürster, M. [0000-0002-1765-9907]; Marfil, E. [0000-0001-8907-4775]; Montes, D. [0000-0002-7779-238X]; Morales, J. C. [0000-0003-0061-518X]; Nagel, E. [0000-0002-4019-3631]; Sarro, L. M. [0000-0002-5622-5191]; Tabernero, H. [0000-0002-8087-4298]; Zechmesister, M. [0000-0002-6532-4378]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Existing and upcoming instrumentation is collecting large amounts of astrophysical data, which require efficient and fast analysis techniques. We present a deep neural network architecture to analyze high-resolution stellar spectra and predict stellar parameters such as effective temperature, surface gravity, metallicity, and rotational velocity. With this study, we firstly demonstrate the capability of deep neural networks to precisely recover stellar parameters from a synthetic training set. Secondly, we analyze the application of this method to observed spectra and the impact of the synthetic gap (i.e., the difference between observed and synthetic spectra) on the estimation of stellar parameters, their errors, and their precision. Our convolutional network is trained on synthetic PHOENIX-ACES spectra in different optical and near-infrared wavelength regions. For each of the four stellar parameters, Teff, log g, [M/H], and v sin i, we constructed a neural network model to estimate each parameter independently. We then applied this method to 50 M dwarfs with high-resolution spectra taken with CARMENES (Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Échelle Spectrographs), which operates in the visible (520–960 nm) and near-infrared wavelength range (960–1710 nm) simultaneously. Our results are compared with literature values for these stars. They show mostly good agreement within the errors, but also exhibit large deviations in some cases, especially for [M/H], pointing out the importance of a better understanding of the synthetic gap.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs Convective shift and starspot constraints from chromatic radial velocities
(EDP Sciences, 2020-09-10) Baroch, D.; Morales, J. C.; Ribas, I.; Herrero, E.; Rosich, A.; Perger, M.; Anglada Escudé, G.; Reiners, A.; Caballero, J. A.; Quirrenbach, A.; Amado, P. J.; Jeffers, S. V.; Cifuentes, C.; Passegger, V. M.; Schweitzer, A.; Lafarga, M.; Bauer, F. F.; Béjar, V. J. S.; Colomé, J.; Cortés Contreras, M.; Dreizler, S.; Galadí Enríquez, D.; Hatzes, A. P.; Henning, T.; Kaminski, A.; Kürster, M.; Montes, D.; Rodríguez López, C.; Zechmeister, M.; Deutsche Forschungsgemeinschaft (DFG); Agencia Estatal de Investigación (AEI); National Aeronautics and Space Administration (NASA); Baroch, D. [0000-0001-7568-5161]; Ribas, I. [0000-0002-6689-0312]; Montes, D. [0000-0002-7779-238X]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709
Context. Variability caused by stellar activity represents a challenge to the discovery and characterization of terrestrial exoplanets and complicates the interpretation of atmospheric planetary signals. Aims. We aim to use a detailed modeling tool to reproduce the effect of active regions on radial velocity measurements, which aids the identification of the key parameters that have an impact on the induced variability. Methods. We analyzed the effect of stellar activity on radial velocities as a function of wavelength by simulating the impact of the properties of spots, shifts induced by convective motions, and rotation. We focused our modeling effort on the active star YZ CMi (GJ 285), which was photometrically and spectroscopically monitored with CARMENES and the Telescopi Joan Oró. Results. We demonstrate that radial velocity curves at different wavelengths yield determinations of key properties of active regions, including spot-filling factor, temperature contrast, and location, thus solving the degeneracy between them. Most notably, our model is also sensitive to convective motions. Results indicate a reduced convective shift for M dwarfs when compared to solar-type stars (in agreement with theoretical extrapolations) and points to a small global convective redshift instead of blueshift. Conclusions. Using a novel approach based on simultaneous chromatic radial velocities and light curves, we can set strong constraints on stellar activity, including an elusive parameter such as the net convective motion effect.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs Different roads to radii and masses of the target stars
(EDP Sciences, 2019-05-14) Schweitzer, A.; Passegger, V. M.; Cifuentes, C.; Béjar, V. J. S.; Cortés Contreras, M.; Caballero, J. A.; Del Burgo, C.; Czesla, S.; Kürster, M.; Montes, D.; Zapatero Osorio, M. R.; Ribas, I.; Reiners, A.; Quirrenbach, A.; Amado, P. J.; Aceituno, J.; Anglada Escudé, G.; Bauer, F. F.; Dreizler, S.; Jeffers, S. V.; Guenther, E. W.; Henning, T.; Kaminski, A.; Lafarga, M.; Marfil, E.; Morales, J. C.; Schmitt, J. H. M. M.; Seifert, W.; Tabernero, H. M.; Zechmeister, M.; Solano, Enrique; Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Deutsche Forschungsgemeinschaft (DFG); Consejo Nacional de Ciencia y Tecnología (CONACYT); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Aims. We determine the radii and masses of 293 nearby, bright M dwarfs of the CARMENES survey. This is the first time that such a large and homogeneous high-resolution (R > 80 000) spectroscopic survey has been used to derive these fundamental stellar parameters. Methods. We derived the radii using Stefan–Boltzmann’s law. We obtained the required effective temperatures Teff from a spectral analysis and we obtained the required luminosities L from integrated broadband photometry together with the Gaia DR2 parallaxes. The mass was then determined using a mass-radius relation that we derived from eclipsing binaries known in the literature. We compared this method with three other methods: (1) We calculated the mass from the radius and the surface gravity log g, which was obtained from the same spectral analysis as Teff. (2) We used a widely used infrared mass-magnitude relation. (3) We used a Bayesian approach to infer stellar parameters from the comparison of the absolute magnitudes and colors of our targets with evolutionary models. Results. Between spectral types M0 V and M7 V our radii cover the range 0.1 R⊙ < R < 0.6 R⊙ with an error of 2–3% and our masses cover 0.09 ℳ⊙ < ℳ< 0.6ℳ⊙ with an error of 3–5%. We find good agreement between the masses determined with these different methods for most of our targets. Only the masses of very young objects show discrepancies. This can be well explained with the assumptions that we used for our methods.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs No evidence for a super-Earth in a 2-day orbit around GJ 1151
(EDP Sciences, 2021-05-07) Perger, M.; Ribas, I.; Anglada Escudé, G.; Morales, J. C.; Amado, P. J.; Caballero, J. A.; Quirrenbach, A.; Reiners, A.; Béjar, V. J. S.; Dreizler, S.; Galadí Enríquez, D.; Hatzes, A. P.; Henning, T.; Jeffers, S. V.; Kaminski, A.; Kürster, M.; Lafarga, M.; Montes, D.; Pallé, E.; Rodríguez López, C.; Schweitzer, A.; Zapatero Osorio, M. R.; Zechmeister, M.; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MINECO/ICTI2013-2016/MDM-2017-0737; Perger, M. [0000-0001-7098-0372]; Montes, D. [0000-0002-7779-238X]; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. The interaction between Earth-like exoplanets and the magnetic field of low-mass host stars are considered to produce weak emission signals at radio frequencies. A study using LOFAR data announced the detection of radio emission from the mid M-type dwarf GJ 1151 that could potentially arise from a close-in terrestrial planet. Recently, the presence of a 2.5-M⊕ planet orbiting GJ 1151 with a 2-day period has been claimed using 69 radial velocities (RVs) from the HARPS-N and HPF instruments. Aims. We have obtained 70 new high-precision RV measurements in the framework of the CARMENES M-dwarf survey and use these data to confirm the presence of the claimed planet and to place limits on possible planetary companions in the GJ 1151 system. Methods. We analysed the periodicities present in the combined RV data sets from all three instruments and calculated the detection limits for potential planets in short-period orbits. Results. We cannot confirm the recently announced candidate planet and conclude that the 2-day signal in the HARPS-N and HPF data sets is most probably produced by a long-term RV variability, possibly arising from an outer planetary companion that has yet to be constrained. We calculate a 99.9% significance detection limit of 1.50 m s−1 in the RV semi-amplitude, which places upper limits of 0.7 M⊕ and 1.2 M⊕ on the minimum masses of potential exoplanets with orbital periods of 1 and 5 days, respectively.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs Period search in Hα, Na I D, and Ca II IRT lines
(EDP Sciences, 2019-02-27) Fuhrmeister, B.; Czesla, S.; Schmitt, J. H. M. M.; Johnson, E. N.; Schöfer, P.; Jeffers, S. V.; Caballero, J. A.; Zechmeister, M.; Reiners, A.; Ribas, I.; Amado, P. J.; Quirrenbach, A.; Bauer, F. F.; Béjar, V. J. S.; Cortés Contreras, M.; Díez Alonso, E.; Dreizler, S.; Galadí Enríquez, D.; Guenther, E. W.; Kaminski, A.; Kürster, M.; Lafarga, M.; Montes, D.; Deutsche Forschungsgemeinschaft (DFG); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We use spectra from CARMENES, the Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs, to search for periods in chromospheric indices in 16 M0–M2 dwarfs. We measure spectral indices in the Hα, the Ca II infrared triplet (IRT), and the Na I D lines to study which of these indices are best-suited to finding rotation periods in these stars. Moreover, we test a number of different period-search algorithms, namely the string length method, the phase dispersion minimisation, the generalized Lomb–Scargle periodogram, and the Gaussian process regression with quasi-periodic kernel. We find periods in four stars using Hα and in five stars using the Ca II IRT, two of which have not been found before. Our results show that both Hα and the Ca II IRT lines are well suited for period searches, with the Ca II IRT index performing slightly better than Hα. Unfortunately, the Na I D lines are strongly affected by telluric airglow, and we could not find any rotation period using this index. Further, different definitions of the line indices have no major impact on the results. Comparing the different search methods, the string length method and the phase dispersion minimisation perform worst, while Gaussian process models produce the smallest numbers of false positives and non-detections.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs Photospheric parameters of target stars from high-resolution spectroscopy. II. Simultaneous multiwavelength range modeling of activity insensitive lines
(EDP Sciences, 2019-07-17) Passegger, V. M.; Schweitzer, A.; Shulyak, D.; Nagel, E.; Hauschildt, P. H.; Reiners, A.; Amado, P. J.; Caballero, J. A.; Cortés Contreras, M.; Domínguez Fernández, A. J.; Quirrenbach, A.; Ribas, I.; Azzaro, M.; Anglada Escudé, G.; Bauer, F. F.; Béjar, V. J. S.; Dreizler, S.; Guenther, E. W.; Henning, T.; Jeffers, S. V.; Kaminski, A.; Kürster, M.; Lafarga, M.; Martín, E. L.; Montes, D.; Morales, J. C.; Schmitt, J. H. M. M.; Zechmeister, M.; Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); Deutsche Forschungsgemeinschaft (DFG); Nvidia; 0000-0002-8388-6040; 0000-0003-3734-9866; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We present precise photospheric parameters of 282 M dwarfs determined from fitting the most recent version of PHOENIX models to high-resolution CARMENES spectra in the visible (0.52–0.96 μm) and NIR wavelength range (0.96–1.71 μm). With its aim to search for habitable planets around M dwarfs, several planets of different masses have been detected. The characterization of the target sample is important for the ability to derive and constrain the physical properties of any planetary systems that are detected. As a continuation of previous work in this context, we derived the fundamental stellar parameters effective temperature, surface gravity, and metallicity of the CARMENES M-dwarf targets from PHOENIX model fits using a χ2 method. We calculated updated PHOENIX stellar atmosphere models that include a new equation of state to especially account for spectral features of low-temperature stellar atmospheres as well as new atomic and molecular line lists. We show the importance of selecting magnetically insensitive lines for fitting to avoid effects of stellar activity in the line profiles. For the first time, we directly compare stellar parameters derived from multiwavelength range spectra, simultaneously observed for the same star. In comparison with literature values we show that fundamental parameters derived from visible spectra and visible and NIR spectra combined are in better agreement than those derived from the same spectra in the NIR alone.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs The He I triplet at 10830 Å across the M dwarf sequence
(EDP Sciences, 2019-11-25) Fuhrmeister, B.; Czesla, S.; Hildebrandt, L.; Nagel, E.; Schmitt, H. M. M.; Hintz, D.; Johnson, E. N.; Sanz Forcada, J.; Schöfer, P.; Jeffers, S. V.; Caballero, J. A.; Zechmeister, M.; Reiners, A.; Ribas, I.; Amado, P. J.; Quirrenbach, A.; Bauer, F. F.; Béjar, V. J. S.; Cortés Contreras, M.; Díez Alonso, E.; Dreizler, S.; Galadí Enríquez, D.; Guenther, E. W.; Kaminski, A.; Kürster, M.; Lafarga, M.; Montes, D.; Deutsche Forschungsgemeinschaft (DFG); Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); Ribas, I. [0000-0002-6689-0312]; Montes, D. [0000-0002-7779-238X]; Lafarga, M. [0000-0002-8815-9416]; Amado, P. [0000-0001-8012-3788]; Nagel, E. [0000-0002-4019-3631]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548
The He I infrared (IR) triplet at 10 830 Å is an important activity indicator for the Sun and in solar-type stars, however, it has rarely been studied in relation to M dwarfs to date. In this study, we use the time-averaged spectra of 319 single stars with spectral types ranging from M0.0 V to M9.0 V obtained with the CARMENES high resolution optical and near-infrared spectrograph at Calar Alto to study the properties of the He I IR triplet lines. In quiescence, we find the triplet in absorption with a decrease of the measured pseudo equivalent width (pEW) towards later sub-types. For stars later than M5.0 V, the He I triplet becomes undetectable in our study. This dependence on effective temperature may be related to a change in chromospheric conditions along the M dwarf sequence. When an emission in the triplet is observed, we attribute it to flaring. The absence of emission during quiescence is consistent with line formation by photo-ionisation and recombination, while flare emission may be caused by collisions within dense material. The He I triplet tends to increase in depth according to increasing activity levels, ultimately becoming filled in; however, we do not find a correlation between the pEW(He IR) and X-ray properties. This behaviour may be attributed to the absence of very inactive stars (LX∕Lbol < −5.5) in our sample or to the complex behaviour with regard to increasing depth and filling in.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs Three temperate-to-warm super-Earths
(EDP Sciences, 2020-11-10) Stock, S.; Nagel, E.; Kemmer, J.; Passegger, V. M.; Reffert, S.; Quirrenbach, A.; Caballero, J. A.; Czesla, S.; Béjar, V. J. S.; Cardona Guillén, C.; Díez Alonso, E.; Herrero, E.; Lalitha, S.; Schlecker, M.; Tal Or, L.; Rodríguez, E.; Rodríguez López, C.; Ribas, I.; Reiners, A.; Amado, P. J.; Bauer, F. F.; Bluhm, P.; Cortés Contreras, M.; González Cuesta, L.; Dreizler, S.; Hatzes, A. P.; Henning, T.; Jeffers, S. V.; Kaminski, A.; Kürster, M.; Lafarga, M.; López González, M. J.; Montes, D.; Morales, J. C.; Pedraz, S.; Schöfer, P.; Schweitzer, A.; Trifonov, T.; Zapatero Osorio, M. R.; Zechmeister, M.; Agencia Estatal de Investigación (AEI); Generalitat de Catalunya; National Aeronautics and Space Administration (NASA); Tel-Aviv University (Israel); Stock, S. [0000-0002-1166-9338]; Nagel, E. [0000-0002-4019-3631]; Kemmer, J. [0000-0003-3929-1442]; Reffert, S. [0000-0002-0460-8289]; Caballero, J. A. [0000-0002-7349-1387]; Cardona, C. [0000-0002-2198-4200]; Schlecker, M. [0000-0001-8355-2107]; Tal Or, L. [0000-0003-3757-1440]; Rodríguez, E. [0000-0001-6827-9077]; Ribas, I. [0000-0002-6689-0312]; Amado, P. J. [0000-0002-8388-6040]; Cortés Contreras, M. [0000-0003-3734-9866]; González Cuesta, L. [0000-0002-1241-5508]; López González, M. J. [0000-0001-8104-5128]; Zapatero Osorio, M. R. [0000-0001-5664-2852]; Zechmeister, M. [0000-0002-6532-4378]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548
We announce the discovery of two planets orbiting the M dwarfs GJ 251 (0.360 ± 0.015M⊙) and HD 238090 (0.578 ± 0.021M⊙) based on CARMENES radial velocity (RV) data. In addition, we independently confirm with CARMENES data the existence of Lalande 21185 b, a planet that has recently been discovered with the SOPHIE spectrograph. All three planets belong to the class of warm or temperate super-Earths and share similar properties. The orbital periods are 14.24 d, 13.67 d, and 12.95 d and the minimum masses are 4.0 ± 0.4 M⊕, 6.9 ± 0.9 M⊕, and 2.7 ± 0.3 M⊕ for GJ 251 b, HD 238090 b, and Lalande 21185 b, respectively. Based on the orbital and stellar properties, we estimate equilibrium temperatures of 351.0 ± 1.4 K for GJ 251 b, 469.6 ± 2.6 K for HD 238090 b, and 370.1 ± 6.8 K for Lalande 21185 b. For the latter we resolve the daily aliases that were present in the SOPHIE data and that hindered an unambiguous determination of the orbital period. We find no significant signals in any of our spectral activity indicators at the planetary periods. The RV observations were accompanied by contemporaneous photometric observations. We derive stellar rotation periods of 122.1 ± 2.2 d and 96.7 ± 3.7 d for GJ 251 and HD 238090, respectively. The RV data of all three stars exhibit significant signals at the rotational period or its first harmonic. For GJ 251 and Lalande 21185, we also find long-period signals around 600 d, and 2900 d, respectively, which we tentatively attribute to long-term magnetic cycles. We apply a Bayesian approach to carefully model the Keplerian signals simultaneously with the stellar activity using Gaussian process regression models and extensively search for additional significant planetary signals hidden behind the stellar activity. Current planet formation theories suggest that the three systems represent a common architecture, consistent with formation following the core accretion paradigm.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs. The He I infrared triplet lines in PHOENIX models of M 2-3 V stars
(EDP Sciences, 2020-06-24) Hintz, D.; Fuhrmeister, B.; Czesla, S.; Schmitt, H. M. M.; Schweitzer, A.; Nagel, E.; Johnson, E. N.; Caballero, J. A.; Zechmeister, M.; Jeffers, S. V.; Reiners, A.; Ribas, I.; Amado, P. J.; Quirrenbach, A.; Anglada Escudé, G.; Bauer, F. F.; Béjar, V. J. S.; Cortés Contreras, M.; Dreizler, S.; Galadí Enríquez, D.; Guenther, E. W.; Hauschildt, P. H.; Kaminski, A.; Kürster, M.; Lafarga, M.; López del Fresno, M.; Montes, D.; Morales, J. C.; Deutsches Zentrum für Luft- und Raumfahrt (DLR); Deutsche Forschungsgemeinschaft (DFG); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); 0000-0002-5274-2589; 0000-0001-6470-2907; 0000-0002-6532-4378; 0000-0003-1212-5225; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The He » I infrared (IR) line at a vacuum wavelength of 10 833 Å is a diagnostic for the investigation of atmospheres of stars and planets orbiting them. For the first time, we study the behavior of the He » I IR line in a set of chromospheric models for M-dwarf stars, whose much denser chromospheres may favor collisions for the level population over photoionization and recombination, which are believed to be dominant in solar-type stars. For this purpose, we use published PHOENIX models for stars of spectral types M2 V and M3 V and also compute new series of models with different levels of activity following an ansatz developed for the case of the Sun. We perform a detailed analysis of the behavior of the He I IR line within these models. We evaluate the line in relation to other chromospheric lines and also the influence of the extreme ultraviolet (EUV) radiation field. The analysis of the He » I IR line strengths as a function of the respective EUV radiation field strengths suggests that the mechanism of photoionization and recombination is necessary to form the line for inactive models, while collisions start to play a role in our most active models. Moreover, the published model set, which is optimized in the ranges of the Na » I D2, Hα, and the bluest Ca » II IR triplet line, gives an adequate prediction of the He » I IR line for most stars of the stellar sample. Because especially the most inactive stars with weak He » I IR lines are fit worst by our models, it seems that our assumption of a 100% filling factor of a single inactive component no longer holds for these stars. © ESO 2020.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs. Variability of the He I line at 10 830 Å
(EDP Sciences, 2020-08-10) Fihrmeister, B.; Czesla, S.; Hildebrandt, L.; Nagel, E.; Schmitt, H. M. M.; Jeffers, S. V.; Caballero, J. A.; Hintz, D.; Johnson, E. N.; Schöfer, P.; Zechmeister, M.; Reiners, A.; Ribas, I.; Amado, P. J.; Quirrenbach, A.; Nortmann, L.; Bauer, F. F.; Béjar, V. J. S.; Cortés Contreras, M.; Dreizler, S.; Galadí Enríquez, D.; Hatzes, A. P.; Kaminski, A.; Kürster, M.; Lafarga, M.; Deutsche Forschungsgemeinschaft (DFG); Bauer, F. F. [0000-0003-1212-5225]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The He I infrared (IR) triplet at 10 830 Å is known as an activity indicator in solar-type stars and has become a primary diagnostic in exoplanetary transmission spectroscopy. He I IR lines are a tracer of the stellar extreme-ultraviolet irradiation from the transition region and corona. We study the variability of the He I triplet lines in a spectral time series of 319 M dwarf stars that was obtained with the CARMENES high-resolution optical and near-infrared spectrograph at Calar Alto. We detect He I IR line variability in 18% of our sample stars, all of which show Hα in emission. Therefore, we find detectable He I variability in 78% of the sub-sample of stars with Hα emission. Detectable variability is strongly concentrated in the latest spectral sub-types, where the He I lines during quiescence are typically weak. The fraction of stars with detectable He I variation remains lower than 10% for stars earlier than M3.0 V, while it exceeds 30% for the later spectral sub-types. Flares are accompanied by particularly pronounced line variations, including strongly broadened lines with red and blue asymmetries. However, we also find evidence for enhanced He I absorption, which is potentially associated with increased high-energy irradiation levels at flare onset. Generally, He I and Hα line variations tend to be correlated, with Hα being the most sensitive indicator in terms of pseudo-equivalent width variation. This makes the He I triplet a favourable target for planetary transmission spectroscopy. © 2020 ESO.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs: A super-Earth planet orbiting HD 79211 (GJ 338 B)
(EDP Sciences, 2020-05-27) González Álvarez, E.; Zapatero Osorio, M. R.; Caballero, J. A.; Sanz Forcada, J.; Béjar, V. J. S.; González Cuesta, L.; Dreizler, S.; Bauer, F. F.; Rodríguez, E.; Tal Or, L.; Zechmeister, M.; Montes, D.; López González, M. J.; Ribas, I.; Reiners, A.; Quirrenbach, A.; Amado, P. J.; Anglada Escudé, G.; Azzaro, M.; Cortés Contreras, M.; Hatzes, A. P.; Henning, T.; Jeffers, S. V.; Kaminski, A.; Kürster, M.; Lafarga, M.; Morales, J. C.; Pallé, E.; Perger, M.; Schmitt, H. M. M.; Agencia Estatal de Investigación (AEI); González Álvarez, E. https://orcid.org/0000-0002-4820-2053; Zapatero Osorio, M. R.https://orcid.org/0000-0001-5664-2852; Caballero, J. A. https://orcid.org/0000-0002-7349-1387; López González, M. J. https://orcid.org/0000-0002-0011-3086; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709
Aims. We report on radial velocity time series for two M0.0 V stars, GJ 338 B and GJ 338 A, using the CARMENES spectrograph, complemented by ground-telescope photometry from Las Cumbres and Sierra Nevada observatories. We aim to explore the presence of small planets in tight orbits using the spectroscopic radial velocity technique. Methods. We obtained 159 and 70 radial velocity measurements of GJ 338 B and A, respectively, with the CARMENES visible channel between 2016 January and 2018 October. We also compiled additional relative radial velocity measurements from the literature and a collection of astrometric data that cover 200 a of observations to solve for the binary orbit. Results. We found dynamical masses of 0.64 ± 0.07 M° for GJ 338 B and 0.69 ± 0.07 M° for GJ 338 A. The CARMENES radial velocity periodograms show significant peaks at 16.61 ± 0.04 d (GJ 338 B) and 16.3-1.3+3.5 d (GJ 338 A), which have counterparts at the same frequencies in CARMENES activity indicators and photometric light curves. We attribute these to stellar rotation. GJ 338 B shows two additional, significant signals at 8.27 ± 0.01 and 24.45 ± 0.02 d, with no obvious counterparts in the stellar activity indices. The former is likely the first harmonic of the star's rotation, while we ascribe the latter to the existence of a super-Earth planet with a minimum mass of 10.27-1.38+1.47 M⊕ orbiting GJ 338 B. We have not detected signals of likely planetary origin around GJ 338 A. Conclusions. GJ 338 Bb lies inside the inner boundary of the habitable zone around its parent star. It is one of the least massive planets ever found around any member of stellar binaries. The masses, spectral types, brightnesses, and even the rotational periods are very similar for both stars, which are likely coeval and formed from the same molecular cloud, yet they differ in the architecture of their planetary systems. © ESO 2020.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs: Characterization of the nearby ultra-compact multiplanetary system YZ Ceti
(EDP Sciences, 2020-05-01) Stock, S.; Kemmer, J.; Reffert, S.; Trifonov, T.; Kaminski, A.; Dreizler, S.; Quirrenbach, A.; Caballero, J. A.; Reiners, A.; Anglada Escudé, G.; Ribas, I.; Amado, P. J.; Barrado, D.; Barnes, J. R.; Bauer, F. F.; Berdiñas, Z. M.; Béjar, V. J. S.; Coleman, G. A. L.; Cortés Contreras, M.; Díez Alonso, E.; Domínguez Fernández, A. J.; Espinoza, N.; Haswell, C. A.; Hatzes, A.; Henning, T.; Jenkins, J. S.; Jones, H. R. A.; Kossakowski, D.; Kürster, M.; Lafarga, M.; Lee, M. H.; López González, M. J.; Montes, D.; Morales, J. C.; Morales, N.; Pallé, E.; Pedraz, S.; Rodríguez, E.; Rodríguez López, C.; Zechmeister, M.; Jeffers, S. V.; Deutsche Forschungsgemeinschaft (DFG); Agencia Estatal de Investigación (AEI); Comisión Nacional de Investigación Científica y Tecnológica (CONICYT); Ministerio de Economía y Competitividad (MINECO); Junta de Andalucía; European Research Council (ERC); Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT); Science and Technology Facilities Council (STFC); Generalitat de Catalunya; 0000-0002-1166-9338; 0000-0003-3929-1442; 0000-0002-0460-8289; 0000-0002-0236-775X; 0000-0003-0203-8208; 0000-0002-7349-1387; 0000-0003-2490-4779; 0000-0002-6689-0312; 0000-0002-8388-6040; 0000-0003-1930-5683; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs: Dynamical characterization of the multiple planet system GJ 1148 and prospects of habitable exomoons around GJ 1148 b
(EDP Sciences, 2020-06-03) Trifonov, T.; Lee, M. H.; Kürster, M.; Henning, T.; Grishin, E.; Stock, S.; Tjoa, J.; Caballero, J. A.; Wong, K. H.; Bauer, F. F.; Quirrenbach, A.; Zechmeister, M.; Ribas, I.; Reffert, S.; Reiners, A.; Amado, P. J.; Kossakowski, D.; Azzaro, M.; Béjar, V. J. S.; Cortés Contreras, M.; Dreizler, S.; Hatzes, A. P.; Jeffers, S. V.; Kaminski, A.; Lafarga, M.; Montes, D.; Morales, J. C.; Pavlov, A.; Rodríguez López, C.; Schmitt, H. M. M.; Barnes, R.; Solano, Enrique; Deutsche Forschungsgemeinschaft (DFG); Ministerio de Economía y Competitividad (MINECO); Junta de Andalucía; European Research Council (ERC); Agencia Estatal de Investigación (AEI); Trifonov, T. https://orcid.org/0000-0002-0236-775X; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709
Context. GJ 1148 is an M-dwarf star hosting a planetary system composed of two Saturn-mass planets in eccentric orbits with periods of 41.38 and 532.02 days. Aims. We reanalyze the orbital configuration and dynamics of the GJ 1148 multi-planetary system based on new precise radial velocity measurements taken with CARMENES. Methods. We combined new and archival precise Doppler measurements from CARMENES with those available from HIRES for GJ 1148 and modeled these data with a self-consistent dynamical model. We studied the orbital dynamics of the system using the secular theory and direct N-body integrations. The prospects of potentially habitable moons around GJ 1148 b were examined. Results. The refined dynamical analyses show that the GJ 1148 system is long-term stable in a large phase-space of orbital parameters with an orbital configuration suggesting apsidal alignment, but not in any particular high-order mean-motion resonant commensurability. GJ 1148 b orbits inside the optimistic habitable zone (HZ). We find only a narrow stability region around the planet where exomoons can exist. However, in this stable region exomoons exhibit quick orbital decay due to tidal interaction with the planet. Conclusions. The GJ 1148 planetary system is a very rare M-dwarf planetary system consisting of a pair of gas giants, the inner of which resides in the HZ. We conclude that habitable exomoons around GJ 1148 b are very unlikely to exist. © 2020 T. Trifonov et al.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs: LP 714-47 b (TOI 442.01): populating the Neptune desert
(EDP Sciences, 2020-12-11) Dreizler, S.; Crossfield, J. M.; Kossakowski, D.; Plavchan, P.; Jeffers, S. V.; Kemmer, J.; Luque, R.; Espinoza, N.; Pallé, E.; Stassun, K.; Matthews, E.; Gorjian, V.; Kawauchi, K.; Kielkopf, J. F.; Hidalgo, D.; Kosiarek, M. R.; Kreidberg, L.; Huber, D.; Livingston, J.; Jehin, E.; Jensen, E. L. N.; Mann, A.; Madrigal Aguado, A.; Kane, S. R.; Mocnik, T.; Morales, J. C.; Klahr, H.; Murgas Alcaino, F.; Kürster, M.; Lafarga, M.; Nowak, G.; Louie, D.; Parviainen, H.; Passegger, V. M.; Matson, R. A.; Pozuelos, F. J.; Quirrenbach, A.; Muirhead, P. S.; Robertson, P.; Nandakumar, S.; Narita, N.; Rose, M. E.; Roy, A.; Oshagh, M.; Schlieder, J.; Shectman, S.; Pollacco, D.; Senavci, H. V.; Reefe, M.; Ribas, I.; Villaseñor, J. N.; Rodríguez López, C.; Weiss, L. M.; Wittrock, J.; Schweitzer, A.; Zohrabi, F.; Cale, B.; Tanner, A.; Lillo Box, J.; Teske, J.; Twicken, J. D.; Lalitha, S.; Reiners, A.; Wang, S. X.; Bitsch, B.; Zapatero Osorio, M. R.; Yilmaz, M.; Ricker, G.; Caballero, J. A.; Schlecker, M.; Seager, S.; Zechmeister, M.; Jenkins, J. M.; Aceituno, J.; Soubkiou, A.; Barkaoui, K.; Chaturvedi, P.; Hatzes, A. P.; Bauer, F. F.; Vanderspek, R.; Latham, D. W.; Benkhaldoun, Z.; Beichman, C.; Winn, J. N.; Butler, R. P.; Caldwell, D. A.; Amado, P. J.; Christianesen, J. L.; Barbieri, M.; Batalha, N. M.; Collins, K. A.; Benneke, B.; Combs, D.; Cortés Contreras, M.; Burt, J.; Daylan, T.; Chintada, A.; Chontos, A.; Evans, P.; Ciardi, D. R.; Cifuentes, C.; Flowers, E. E.; Fukui, A.; Collins, K. I.; Furlan, E.; Gaidos, E.; Crane, J. D.; Gillon, M.; Dragomir, D.; Esparza Borges, E.; Hellier, C.; Feng, F.; Howard, A. W.; Howell, Steve B.; Fulton, B.; Isaacson, I.; Geneser, C.; Giacalone, S.; Kaminski, A.; Gonzales, E.; Junta de Andalucia; National Aeronautics and Space Administration (NASA); European Research Council (ERC); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Generalitat de Catalunya; Science and Technology Facilities Council (STFC); Centre National de la Recherche Scientifique (CNRS); Japan Society for the Promotion of Science (KAKENHI); 0000-0001-6187-5941; 0000-0002-8864-1667; 0000-0003-3929-1442; 0000-0003-0987-1593; 0000-0002-7349-1387; 0000-0003-3742-1987; 0000-0002-8388-6040; 0000-0003-1715-5087; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We report the discovery of a Neptune-like planet (LP 714-47 b, P = 4.05204 d, m(b) = 30.8 +/- 1.5M(circle plus), R-b = 4.7 +/- 0.3 R-circle plus) located in the "hot Neptune desert". Confirmation of the TESS Object of Interest (TOI 442.01) was achieved with radial-velocity follow-up using CARMENES, ESPRESSO, HIRES, iSHELL, and PFS, as well as from photometric data using TESS, Spitzer, and ground-based photometry from MuSCAT2, TRAPPIST-South, MONET-South, the George Mason University telescope, the Las Cumbres Observatory Global Telescope network, the El Sauce telescope, the TuBTAK National Observatory, the University of Louisville Manner Telescope, and WASP-South. We also present high-spatial resolution adaptive optics imaging with the Gemini Near-Infrared Imager. The low uncertainties in the mass and radius determination place LP 714-47 b among physically well-characterised planets, allowing for a meaningful comparison with planet structure models. The host star LP 714-47 is a slowly rotating early M dwarf (T-eff = 3950 +/- 51 K) with a mass of 0.59 +/- 0.02M(circle dot) and a radius of 0.58 +/- 0.02R(circle dot). From long-term photometric monitoring and spectroscopic activity indicators, we determine a stellar rotation period of about 33 d. The stellar activity is also manifested as correlated noise in the radial-velocity data. In the power spectrum of the radial-velocity data, we detect a second signal with a period of 16 days in addition to the four-day signal of the planet. This could be shown to be a harmonic of the stellar rotation period or the signal of a second planet. It may be possible to tell the difference once more TESS data and radial-velocity data are obtained.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs: Measuring precise radial velocities in the near infrared: The example of the super-Earth CD Cet b
(EDP Sciences, 2020-08-10) Bauer, F. F.; Zechmeister, M.; Kaminski, A.; Rodríguez López, C.; Caballero, J. A.; Azzaro, M.; Stahl, S.; Kossakowski, D.; Quirrenbach, A.; Becerril Jarque, S.; Rodríguez, E.; Amado, P. J.; Seifert, W.; Reiners, A.; Schäfer, S.; Ribas, I.; Béjar, V. J. S.; Cortés Contreras, M.; Dreizler, S.; Hatzes, A.; Henning, T.; Jeffers, S. V.; Kürster, M.; Lafarga, M.; Montes, D.; Morales, J. C.; Schmitt, H. M. M.; Schweitzer, A.; Solano, Enrique; European Research Council (ERC); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Deutsche Forschungsgemeinschaft (DFG); 0000-0003-1212-5225; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548
The high-resolution, dual channel, visible and near-infrared spectrograph CARMENES offers exciting opportunities for stellar and exoplanetary research on M dwarfs. In this work we address the challenge of reaching the highest radial velocity precision possible with a complex, actively cooled, cryogenic instrument, such as the near-infrared channel. We describe the performance of the instrument and the work flow used to derive precise Doppler measurements from the spectra. The capability of both CARMENES channels to detect small exoplanets is demonstrated with the example of the nearby M5.0 V star CD Cet (GJ 1057), around which we announce a super-Earth (4.0 ± 0.4 M· ) companion on a 2.29 d orbit. © 2020 ESO.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs: Radial velocities and activity indicators from cross-correlation functions with weighted binary masks
(EDP Sciences, 2020-04-13) Lafarga, M.; Ribas, I.; Lovis, C.; Perger, M.; Zechmeister, M.; Bauer, F.; Kürster, M.; Cortés Contreras, M.; Morales, J. C.; Herrero, E.; Rosich, A.; Baroch, D.; Reiners, A.; Caballero, J. A.; Quirrenbach, A.; Amado, P. J.; Alacid, J. M.; Béjar, V. J. S.; Dreizler, S.; Hatzes, A. P.; Henning, T.; Jeffers, S. V.; Kaminski, A.; Montes, D.; Pedraz, S.; Rodríguez López, C.; Schmitt, H. M. M.; 0000-0002-8815-9416; 0000-0002-6532-4378; 0000-0002-7349-1387; 0000-0001-9224-0455; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. For years, the standard procedure to measure radial velocities (RVs) of spectral observations consisted in cross-correlating the spectra with a binary mask, that is, a simple stellar template that contains information on the position and strength of stellar absorption lines. The cross-correlation function (CCF) profiles also provide several indicators of stellar activity. Aims. We present a methodology to first build weighted binary masks and, second, to compute the CCF of spectral observations with these masks from which we derive radial velocities and activity indicators. These methods are implemented in a python code that is publicly available. Methods. To build the masks, we selected a large number of sharp absorption lines based on the profile of the minima present in high signal-to-noise ratio (S/N) spectrum templates built from observations of reference stars. We computed the CCFs of observed spectra and derived RVs and the following three standard activity indicators: full-width-at-half-maximum as well as contrast and bisector inverse slope. Results. We applied our methodology to CARMENES high-resolution spectra and obtain RV and activity indicator time series of more than 300 M dwarf stars observed for the main CARMENES survey. Compared with the standard CARMENES template matching pipeline, in general we obtain more precise RVs in the cases where the template used in the standard pipeline did not have enough S/N. We also show the behaviour of the three activity indicators for the active star YZ CMi and estimate the absolute RV of the M dwarfs analysed using the CCF RVs. © ESO 2020.