Examinando por Autor "Perger, M."

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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, Enrique; Rodríguez, E.; López González, M. J.; Rodríguez López, C.; Stock, S.; Zechmeister, M.; Luque, R.; Gesa, L.; Pedraz, S.; Baroch, D.; Sarkis, P.; Lafarga, M.; Johnson, E. N.; Anglada Escudé, G.; González Álvarez, E.; Perryman, M. A. C.; Dreizler, S.; Sarmiento, L. F.; Tal Or, L.; Labarga, F.; Reffert, S.; Rebolo, R.; Schweitzer, A.; Schäfer, S.; Hagen, H. J.; Lázaro, F. J.; Quirrenbach, A.; Perger, M.; Guenther, E. W.; Schlecker, M.; Montes, D.; Jeffers, S. V.; Cortés Contreras, M.; Kürster, M.; Schmitt, J. H. M. M.; Aceituno, Francisco José; Abellán, F. J.; Rosich, A.; Aceituno, J.; Schöfer, P.; Arroyo Torres, B.; Amado, P. J.; Antona, R.; Solano, Enrique; Benítez, D.; Kaminski, A.; Becerril Jarque, S.; Sota, A.; Kehr, M.; Abril, M.; Brinkmöller, M.; Béjar, V. J. S.; Ammler von Eiff, M.; Calvo Ortega, R.; Zapatero Osorio, M. R.; Barrado, D.; Cardona Guillén, C.; Yan, F.; Bergond, G.; Casanova, V.; Klahr, H.; Chaturvedi, P.; Nagel, E.; Claret, A.; Trifonov, T.; Czesla, S.; Henning, T.; Dorda, R.; Seifert, W.; Fernández Hernández, Maite; Alonso Floriano, F. J.; Azzaro, M.; Berdiñas, Z. M.; Del Burgo, C.; Cano, J.; Carro, J.; Casasayas Barris, N.; Cifuentes, C.; Colomé, J.; Díez Alonso, E.; Emsenhuber, A.; Guàrdia, J.; Guijarro, A.; De Guindos, E.; Hatzes, Artie; Hauschildt, P. H.; Hedrosa, R. P.; Hermelo, I.; Hernández Arabi, R.; Hernández Otero, F.; Hintz, D.; Klüter, J.; González Peinado, R.; González Hernández, J. I.; González Cuesta, L.; De Juan, E.; Stahl, O.; Burn, R.; Kim, M.; Fernández Martín, A.; Lara, L. M.; Mordasini, C.; Labiche, N.; Cárdenas, M. C.; Lampón, M.; Ferro, I. M.; López del Fresno, M.; Passegger, V. M.; Lizon, Jean Louis; Casal, E.; Lodieu, N.; Fuhrmeister, B.; Mancini, L.; López Santiago, J.; Kemmer, J.; Mall, U.; Galadí Enríquez, D.; Martín Fernández, P.; Marfil, E.; Lalitha, S.; Martín, Eduardo L.; Gallardo Cava, I.; Mirabet, E.; Llamas, M.; Marvin, E. L.; García Vargas, M. L.; Nortmann, L.; Magán Madinabeitia, H.; Nelson, Richard; García Piquer, A.; Pallé, E.; Marín Molina, J. A.; Pascual Granado, J.; Caballero, J. A.; Martínez Rodríguez, H.; Pérez Medialdea, D.; Huke, P.; Naranjo, V.; Rabaza, O.; Huber, A.; Ofir, A.; Redondo, P.; Holgado, G.; Rodler, F.; Klutsch, A.; Sabotta, S.; Launhardt, R.; Salz, M.; López Salas, F. J.; Sánchez Carrasco, M. A.; Mandel, H.; Sanz Forcada, J.; Martín Ruiz, S.; Moya, A.; Nowak, G.; Pavlov, Alexander; Pérez Calpena, A.; Ramón Ballesta, A.; Rix, H. W.; Rodríguez Trinidad, A.; Sadegi, S.; Sánchez Blanco, E.; Sánchez López, A.; Stürmer, J.; Suárez, J. C.; Tabernero, H. M.; Tulloch, S. M.; Veredas, G.; Vico Linares, J. I.; Vilardell, F.; Wagner, K.; Winkler, J.; Wolthoff, V.; Johansen, A.; Stuber, T.; 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]; Sarkis, P. [0000-0001-8128-3126]; López Santiago, J. [0000-0003-2402-8166]; Vilardell, F. [0000-0003-0441-1504]; Winkler, J. [0000-0003-0568-8820]; Nowak, G. [0000-0002-7031-7754]; Béjar, V. J. S. [0000-0002-5086-4232]; Luque, R. [0000-0002-4671-2957]; Pérez Calpena, A. [0000-0001-7361-9240]; Sota, A. [https://orcid.org/0000-0002-9404-6952]; Klahr, H. [0000-0002-8227-5467]; Mordasini, C. [0000-0002-1013-2811]; Rodler, F. [0000-0003-0650-5723]; Tabernero, H. [0000-0002-8087-4298]; Cortés Contreras, M. [0000-0003-3734-9866]; Lafarga, M. [0000-0002-8815-9416]; Sánchez López, A. [0000-0002-0516-7956]; Yan, F. [0000-0001-9585-9034]; Reffert, S. [0000-0002-0460-8289]; Rosich, A. [0000-0002-9141-3067]; Sarmiento, L. F. [0000-0002-8475-9705]; Perger, M. [0000-0001-7098-0372]; Sabotta, S. [0000-0001-9078-5574]; Guenther, E. W. [0000-0002-9130-6747]; Kaminski, A. [0000-0003-0203-8208]; Schmitt, J. H. M. M. [0000-0003-2554-9916]; Aceituno, J. [0000-0003-0487-1105]; Alonso Floriano, F. J. [0000-0003-1202-5734]; Stock, S. [0000-0002-1166-9338]; Nagel, E. [0000-0002-4019-3631]; Barrado, D. [0000-0002-5971-9242]; Tulloch, S. [0000-0003-0840-8521]; Trifonov, T. [0000-0002-0236-775X]; Bergond, G. [0000-0003-3132-9215]; Burn, R. [0000-0002-9020-7309]; Zapatero Osorio, M. R. [0000-0001-5664-2852]; Montes, D. [0000-0002-7779-238X]; Cano, J. [0000-0003-1984-5401]; Cardona Guillén, C. [0000-0002-2198-4200]; Baroch, D. [0000-0001-7568-5161]; Ammler-von Eiff, M. [0000-0001-9565-1698]; Chaturvedi, P. [0000-0002-1887-1192]; Cifuentes, C. [0000-0003-1715-5087]; Anglada Escudé, G. [0000-0002-3645-5977]; Becerril Jarque, S. [0000-0001-9009-1150]; González Cuesta, L. [0000-0002-1241-5508]; Díez Alonso, E. [0000-0002-5826-9892]; Emsenhuber, A. [0000-0002-8811-1914]; Passegger, V. M. [0000-0002-8569-7243]; García Vargas, M. L. [0000-0002-2058-3528]; González Álvarez, E. [0000-0002-4820-2053]; Amado, P. J. [0000-0002-8388-6040]; Carro, J. [0000-0002-0838-3603]; Guàrdia, J. [0000-0002-7191-9001]; Abellán, F. J. [0000-0002-5724-1636]; Colomé, J. [0000-0002-1678-2241]; Hermelo, I. [0000-0001-9178-694X]; Hintz, D. [0000-0002-5274-2589]; Arroyo Torres, B. [0000-0002-3392-4694]; Fuhrmeister, B. [0000-0001-8321-5514]; Johnson, E. [0000-0003-2260-5134]; De Juan Fernández, E. [0000-0002-9382-4505]; Berdiñas, Z. M. [0000-0002-6057-6461]; González Hernández, J. I. [0000-0002-0264-7356]; Klüter, J. [0000-0002-3469-5133]; Klutsch, A. [0000-0001-7869-3888]; Calvo Ortega, R. [0000-0003-3693-6030]; Guijarro, A. [0000-0001-5518-1759]; Aceituno, F. J. [0000-0001-8074-4760]; Lara, L. M. [0000-0002-7184-920X]; Launhardt, R. [0000-0002-8298-2663]; Casasayas Barris, N. [0000-0002-2891-8222]; López del Fresno, M. [0000-0002-9479-7780]; Magan Madinabeitia, H. [0000-0003-1243-4597]; Czesla, S. [0000-0002-4203-4773]; Kehr, M. [0000-0002-7420-7368]; Marín Molina, J. A. [0000-0002-3525-0806]; Galadí Enríquez, D. [0000-0003-4946-5653]; Labarga, F. [0000-0002-7143-0206]; Martínez Rodríguez, H. [0000-0002-1919-228X]; Marvin, C. J. [0000-0002-2249-2611]; González Peinado, R. [0000-0002-6658-8930]; Lizon, J. L. [0000-0001-8928-2566]; Naranjo, V. [0000-0003-0097-1061]; Nelson, R. [0000-0002-9687-8779]; De Guindos, E. [0000-0002-8124-9101]; Manici, L. [0000-0002-9428-8732]; Ofir, A. [0000-0002-9152-5042]; Pascual Granado, J. [0000-0003-0139-6951]; Huke, P. [0000-0001-5913-2743]; Martín, E. [0000-0002-1208-4833]; García Piquer, A. [0000-0002-6872-4262]; Rabaza, O. [0000-0003-2766-2103]; Ramón Ballesta, A. [0000-0002-4323-0610]; Kim, M. [0000-0001-6218-2004]; Rodríguez Trinidad, A. [0000-0002-3356-8634]; Sadegi, S. [0000-0001-9897-6121]; Lampón, M. [0000-0002-0183-7158]; Nortmann, L. [0000-0001-8419-8760]; Sanz Forcada, J. [0000-0002-1600-7835]; Lodieu, N. [0000-0002-3612-8968]; Pedraz, S. [0000-0003-1346-208X]; Schäfer, S. [0000-0001-8597-8048]; Schlecker, M. [0000-0001-8355-2107]; Marfil, E. [0000-0001-8907-4775]; Redondo, P. G. [0000-0001-5992-5778]; Schöfer, P. [0000-0002-5969-3708]; Solano, E. [0000-0003-1885-5130]; Martín Ruiz, S. [0000-0002-9006-7182]; Sánchez Carrasco, M. A. [0000-0001-5533-3660]; Stuber, T. [0000-0003-2185-0525]; Suárez, J. C. [0000-0003-3649-8384]; Moya, A. [0000-0003-1665-5389]; 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
Acceso Abierto
A super-Earth on a close-in orbit around the M1V star GJ 740 A HADES and CARMENES collaboration
(EDP Sciences, 2021-04-07) Toledo Padrón, B.; Suárez Mascareño, A.; González Hernández, J. I.; Rebolo, R.; Pinamonti, M.; Perger, M.; Scandariato, G.; Damasso, M.; Sozzetti, A.; Moldonado, J.; Desidera, S.; Ribas, I.; Micela, G.; Affer, L.; González Álvarez, E.; Leto, G.; Pagano, I.; Zanmar Sánchez, R.; Giacobbe, P.; Herrero, Enrique; Morales, J. C.; Amado, P. J.; Caballero, J. A.; Quirrenbach, A.; Reiners, A.; Zechmeister, M.; Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Generalitat de Catalunya
Context. M-dwarfs have proven to be ideal targets for planetary radial velocity (RV) searches due to their higher planet-star mass contrast, which favors the detection of low-mass planets. The abundance of super-Earth and Earth-like planets detected around this type of star motivates further such research on hosts without reported planetary companions. Aims. The HADES and CARMENES programs are aimed at carrying out extensive searches of exoplanetary systems around M-type stars in the northern hemisphere, allowing us to address, in a statistical sense, the properties of the planets orbiting these objects. In this work, we perform a spectroscopic and photometric study of one of the program stars (GJ 740), which exhibits a short-period RV signal that is compatible with a planetary companion. Methods. We carried out a spectroscopic analysis based on 129 HARPS-N spectra taken over a time span of 6 yr combined with 57 HARPS spectra taken over 4 yr, as well as 32 CARMENES spectra taken during more than 1 yr, resulting in a dataset with a time coverage of 10 yr. We also relied on 459 measurements from the public ASAS survey with a time-coverage of 8 yr, along with 5 yr of photometric magnitudes from the EXORAP project taken in the V, B, R, and I filters to carry out a photometric study. Both analyses were made using Markov chain Monte Carlo simulations and Gaussian process regression to model the activity of the star. Results. We present the discovery of a short-period super-Earth with an orbital period of 2.37756−0.00011+0.00013 d and a minimum mass of 2.96−0.48+0.50 M⊕. We offer an update to the previously reported characterization of the magnetic cycle and rotation period of the star, obtaining values of Prot = 35.563 ± 0.071 d and Pcycle = 2800 ± 150 d. Furthermore, the RV time series exhibits a possibly periodic long-term signal, which might be related to a Saturn-mass planet of ~100 M⊕.
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.; González Hernández, J. I.; Guenther, E. W.; Henning, T.; Herrero, Enrique; 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.; 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
HADES RV Programme with HARPS-N at TNG XIII. A sub-Neptune around the M dwarf GJ 720 A
(EDP Sciences, 2021-05-31) González Álvarez, E.; Petralia, A.; Micela, G.; Maldonado, J.; Affer, L.; Maggio, A.; Covino, E.; Damasso, M.; Lanza, A. F.; Perger, M.; Pinamonti, M.; Poretti, E.; Scandariato, G.; Sozzetti, A.; Bignamini, A.; Giacobbe, P.; Leto, G.; Pagano, I.; Zanmar Sánchez, R.; González Hernández, J. I.; Rebolo, R.; Ribas, I.; Suárez Mascareño, A.; Toledo Padrón, B.; National Science Foundation (USA NSF); Agenzia Spaziale Italiana (ASI); Generalitat de Catalunya; Fundación Caixa; Agencia Estatal de Investigación (AEI); González Álvarez, E. [0000-0002-4820-2053]; Petralia, A. [0000-0002-9882-1020]; Maldonado, J. [0000-0002-2218-5689]; Affer, L. [0000-0001-5600-3778]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. The high number of super-Earth and Earth-like planets in the habitable zone detected around M-dwarf stars in recent years has revealed these stellar objects to be the key to planetary radial velocity (RV) searches. Aims. Using the HARPS-N spectrograph within The HArps-n red Dwarf Exoplanet Survey (HADES) we have reached the precision needed to detect small planets with a few Earth masses using the spectroscopic radial velocity technique. HADES is mainly focused on the M-dwarf population of the northern hemisphere. Methods. We obtained 138 HARPS-N RV measurements between 2013 May and 2020 September of GJ 720 A, classified as an M0.5 V star located at a distance of 15.56 pc. To characterize the stellar variability and to distinguish the periodic variation due to the Keplerian signals from those related to stellar activity, the HARPS-N spectroscopic activity indicators and the simultaneous photometric observations with the APACHE and EXORAP transit surveys were analyzed. We also took advantage of TESS, MEarth, and SuperWASP photometric surveys. The combined analysis of HARPS-N RVs and activity indicators let us address the nature of the periodic signals. The final model and the orbital planetary parameters were obtained by simultaneously fitting the stellar variability and the Keplerian signal using a Gaussian process regression and following a Bayesian criterion. Results. The HARPS-N RV periodic signals around 40 days and 100 days have counterparts at the same frequencies in HARPS-N activity indicators and photometric light curves. We thus attribute these periodicities to stellar activity; the first period is likely associated with the stellar rotation. GJ 720 A shows the most significant signal at 19.466 ± 0.005 days with no counterparts in any stellar activity indices. We hence ascribe this RV signal, having a semi-amplitude of 4.72 ± 0.27 m s−1, to the presence of a sub-Neptune mass planet. The planet GJ 720 Ab has a minimum mass of 13.64 ± 0.79 M⊕, it is in circular orbit at 0.119 ± 0.002 AU from its parent star, and lies inside the inner boundary of the habitable zone around its parent star.
Acceso Abierto
HADES RV programme with HARPS-N at TNG XIV. A candidate super-Earth orbiting the M-dwarf GJ 9689 with a period close to half the stellar rotation period
(EDP Sciences, 2021-07-12) Maldonado, J.; Petralia, A.; Damasso, M.; Pinamonti, M.; Scandariato, G.; González Álvarez, E.; Affer, L.; Micela, G.; Lanza, A. F.; Leto, G.; Poretti, E.; Sozzetti, A.; Perger, M.; Giacobbe, P.; Zanmar Sánchez, R.; Maggio, A.; González Hernández, J. I.; Rebolo, R.; Ribas, I.; Suárez Mascareño, A.; Toledo Padrón, B.; Bignamini, A.; Molinari, E.; Covino, E.; Claudi, R.; Desidera, S.; Herrero, Enrique; Morales, J. C.; Pagano, I.; Piotto, G.; Agencia Estatal de Investigación (AEI); Generalitat de Catalunya; Maldonado, J. [0000-0002-2218-5689]; Petralia, A. [0000-0002-9882-1020]; Damasso, M. [0000-0001-9984-4278]; Pinamonti, M. [0000-0002-4445-1845]; Affer, L. [0000-0001-5600-3778]; Lanza, A. F. [0000-0001-5928-7251]; Leto, G. [0000-0002-0040-5011]; Poretti, E. [0000-0003-1200-0473]; Sozzetti, A. [0000-0002-7504-365X]; Perger, M. [0000-0001-7098-0372]; Zanmar Sánchez, R. [0000-0002-6997-0887]; Maggio, A. [0000-0001-5154-6108]; González Hernández, J. I. [0000-0002-0264-7356]; Ribas, I. [0000-0002-6689-0312]; Toledo Padrón, B. [0000-0002-8194-215X]; Bignamini, A. [0000-0002-5606-6354]; Molinari, E. [0000-0002-1742-7735]; Covino, E. [0000-0002-7579-2298]; Claudi, R. [0000-0001-7707-5105]; Desidera, S. [0000-0001-8613-2589]
Context. It is now well-established that small, rocky planets are common around low-mass stars. However, the detection of such planets is challenged by the short-term activity of host stars. Aims. The HARPS-N red Dwarf Exoplanet Survey programme is a long-term project at the Telescopio Nazionale Galileo aimed at monitoring nearby, early-type, M dwarfs, using the HARPS-N spectrograph to search for small, rocky planets. Methods. A total of 174 HARPS-N spectroscopic observations of the M0.5V-type star GJ 9689 taken over the past seven years have been analysed. We combined these data with photometric measurements to disentangle signals related to the stellar activity of the star from possible Keplerian signals in the radial velocity data. We ran an MCMC analysis, applying Gaussian process regression techniques to model the signals present in the data. Results. We identify two periodic signals in the radial velocity time series, with periods of 18.27 and 39.31 d. The analysis of the activity indexes, photometric data, and wavelength dependency of the signals reveals that the 39.31 d signal corresponds to the stellar rotation period. On the other hand, the 18.27 d signal shows no relation to any activity proxy or the first harmonic of the rotation period. We, therefore, identify it as a genuine Keplerian signal. The best-fit model describing the newly found planet, GJ 9689 b, corresponds to an orbital period of Pb = 18.27 ± 0.01 d and a minimum mass of MP sini = 9.65 ± 1.41 M⊕.
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, Enrique; 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, Artie; 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 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, Artie; 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: 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, Artie; 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: 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. F.; Kürster, M.; Cortés Contreras, M.; Morales, J. C.; Herrero, Enrique; Rosich, A.; Baroch, D.; Reiners, A.; Caballero, J. A.; Quirrenbach, A.; Amado, P. J.; Alacid, J. M.; Béjar, V. J. S.; Dreizler, S.; Hatzes, Artie; 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.