Examinando por Autor "Ribas, I."

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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 He I upper atmosphere around the warm Neptune GJ 3470 b
(EDP Sciences, 2020-06-11) Pallé, E.; Nortmann, L.; Casasayas Barris, N.; Lampón, M.; López Puertas, M.; Caballero, J. A.; Sanz Forcada, J.; Lara, L. M.; Nagel, E.; Yan, F.; Alonso Floriano, F. J.; Amado, P. J.; Chen, G.; Cifuentes, C.; Cortés Contreras, M.; Czesla, S.; Molaverdikhani, K.; Montes, D.; Passegger, V. M.; Quirrenbach, A.; Reiners, A.; Ribas, I.; Sánchez López, A.; Schweitzer, A.; Strangret, M.; Zapatero Osorio, M. R.; Zechmeister, M.; Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); National Natural Science Foundation of China (NSFC); 0000-0003-0987-1593; 0000-0002-2891-8222; 0000-0003-2941-7734; 0000-0002-7349-1387; 0000-0003-3734-9866; 0000-0001-5664-2852; 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
High resolution transit spectroscopy has proven to be a reliable technique for the characterization of the chemical composition of exoplanet atmospheres. Taking advantage of the broad spectral coverage of the CARMENES spectrograph, we initiated a survey aimed at characterizing a broad range of planetary systems. Here, we report our observations of three transits of GJ 3470 b with CARMENES in search of He (2(3)S) absorption. On one of the nights, the He & x202f;Iregion was heavily contaminated by OH(-)telluric emission and, thus, it was not useful for our purposes. The remaining two nights had a very different signal-to-noise ratio (S/N) due to weather. They both indicate the presence of He (2(3)S) absorption in the transmission spectrum of GJ 3470 b, although a statistically valid detection can only be claimed for the night with higher S/N. For that night, we retrieved a 1.5 +/- 0.3% absorption depth, translating into aR(p)(lambda)/R-p= 1.15 +/- 0.14 at this wavelength. Spectro-photometric light curves for this same night also indicate the presence of extra absorption during the planetary transit with a consistent absorption depth. The He (2(3)S) absorption is modeled in detail using a radiative transfer code, and the results of our modeling efforts are compared to the observations. We find that the mass-loss rate,& x1e40;, is confined to a range of 3 x 10(10)g s(-1)forT= 6000 K to 10 x 10(10)g s(-1)forT= 9000 K. We discuss the physical mechanisms and implications of the He & x202f;Idetection in GJ 3470 b and put it in context as compared to similar detections and non-detections in other Neptune-size planets. We also present improved stellar and planetary parameter determinations based on our visible and near-infrared observations. © ESO 2020.
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
Analysis of apsidal motion in eclipsing binaries using TESS data I. A test of gravitational theories
(EDP Sciences, 2021-05-12) Baroch, D.; Giménez, Á.; Ribas, I.; Morales, J. C.; Anglada Escudé, G.; Claret, A.; Agencia Estatal de Investigación (AEI); National Aeronautics and Space Administration (NASA); Generalitat de Catalunya
Context. The change in the argument of periastron of eclipsing binaries, that is, the apsidal motion caused by classical and relativistic effects, can be measured from variations in the difference between the time of minimum light of the primary and secondary eclipses. Poor apsidal motion rate determinations and large uncertainties in the classical term have hampered previous attempts to determine the general relativistic term with sufficient precision to test general relativity predictions. Aims. As a product of the TESS mission, thousands of high-precision light curves from eclipsing binaries are now available. Using a selection of suitable well-studied eccentric eclipsing binary systems, we aim to determine their apsidal motion rates and place constraints on key gravitational parameters. Methods. We compute the time of minimum light from the TESS light curves of 15 eclipsing binaries with precise absolute parameters and with an expected general relativistic contribution to the total apsidal motion rate of greater than 60%. We use the changing primary and secondary eclipse timing differences over time to compute the apsidal motion rate, when possible, or the difference between the linear periods as computed from primary and secondary eclipses. For a greater time baseline we carefully combine the high-precision TESS timings with archival reliable timings. Results. We determine the apsidal motion rate of 9 eclipsing binaries, 5 of which are reported for the first time. From these, we are able to measure the general relativistic apsidal motion rate of 6 systems with sufficient precision to test general relativity for the first time using this method. This test explores a regime of gravitational forces and potentials that had not been probed before. We find perfect agreement with theoretical predictions, and we are able to set stringent constraints on two parameters of the parametrised post-Newtonian formalism.
Acceso Abierto
CARMENES input catalog of M dwarfs VI. A time-resolved Ca II H&K catalog from archival data
(EDP Sciences, 2021-08-20) Perdelwitz, V.; Mittag, M.; Tal Or, L.; Schmitt, J. H. M. M.; Caballero, J. A.; Jeffers, S. V.; Reiners, A.; Schweitzer, A.; Trifonov, T.; Ribas, I.; Quirrenbach, A.; Amado, P. J.; Seifert, W.; Cifuentes, C.; Cortés Contreras, M.; Montes, D.; Revilla, D.; Skrzypinski, S. L.; Agencia Estatal de Investigación (AEI); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC; Centro de Excelencia Científica Severo Ochoa Instituto de Astrofísica de Canarias; Perdelwitz, V. [0000-0002-6859-0882]; Tal Or, L. [0000-0003-3757-1440]; Caballero, J. A. [0000-0002-7349-1387]; Reiners, A. [0000-0003-1242-5922]; Schweitzer, A. [0000-0002-1624-0389]; Ribas, I. [0000-0002-6689-0312]; Amado, P. J. [0000-0001-8012-3788]; Cifuentes, C. [0000-0003-1715-5087]; Cortés Contreras, M. [0000-0003-3734-9866]; Skrzypinski, S. L. [0000-0002-0926-9888]; 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
Context. Radial-velocity (RV) jitter caused by stellar magnetic activity is an important factor in state-of-the-art exoplanet discovery surveys such as CARMENES. Stellar rotation, along with heterogeneities in the photosphere and chromosphere caused by activity, can result in false-positive planet detections. Hence, it is necessary to determine the stellar rotation period and compare it to any putative planetary RV signature. Long-term measurements of activity indicators such as the chromospheric emission in the Ca II H&K lines (RHK′) enable the identification of magnetic activity cycles. Aims. In order to determine stellar rotation periods and study the long-term behavior of magnetic activity of the CARMENES guaranteed time observations (GTO) sample, it is advantageous to extract RHK′ time series from archival data, since the CARMENES spectrograph does not cover the blue range of the stellar spectrum containing the Ca II H&K lines. Methods. We have assembled a catalog of 11 634 archival spectra of 186 M dwarfs acquired by seven different instruments covering the Ca II H&K regime: ESPaDOnS, FEROS, HARPS, HIRES, NARVAL, TIGRE, and UVES. The relative chromospheric flux in these lines, RHK′, was directly extracted from the spectra by rectification with PHOENIX synthetic spectra via narrow passbands around the Ca II H&K line cores. Results. The combination of archival spectra from various instruments results in time series for 186 stars from the CARMENES GTO sample. As an example of the use of the catalog, we report the tentative discovery of three previously unknown activity cycles of M dwarfs. Conclusions. We conclude that the method of extracting with the use of model spectra yields consistent results for different instruments and that the compilation of this catalog will enable the analysis of long-term activity time series for a large number of M dwarfs.
Acceso Abierto
CARMENES input catalogue of M dwarfs: V. Luminosities, colours, and spectral energy distributions
(EDP Sciences, 2020-10-12) Cifuentes, C.; Caballero, J. A.; Cortés Contreras, M.; Montes, D.; Abellán, F. J.; Dorda, R.; Holgado, G.; Zapatero Osorio, M. R.; Morales, J. C.; Amado, P. J.; Passegger, V. M.; Quirrenbach, A.; Reiners, A.; Ribas, I.; Sanz Forcada, J.; Schweitzer, A.; Seifert, W.; Solano, E.; Solano, Enrique; Agencia Estatal de Investigación (AEI); National Aeronautics and Space Administration (NASA); 0000-0003-1715-5087; 0000-0002-7349-1387; 0000-0003-3734-9866; 0000-0002-7779-238X; 0000-0001-5664-2852; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. The relevance of M dwarfs in the search for potentially habitable Earth-sized planets has grown significantly in the last years. Aims. In our on-going effort to comprehensively and accurately characterise confirmed and potential planet-hosting M dwarfs, in particular for the CARMENES survey, we have carried out a comprehensive multi-band photometric analysis involving spectral energy distributions, luminosities, absolute magnitudes, colours, and spectral types, from which we have derived basic astrophysical parameters. Methods. We have carefully compiled photometry in 20 passbands from the ultraviolet to the mid-infrared, and combined it with the latest parallactic distances and close-multiplicity information, mostly from Gaia DR2, of a sample of 2479 K5 V to L8 stars and ultracool dwarfs, including 2210 nearby, bright M dwarfs. For this, we made extensive use of Virtual Observatory tools. Results. We have homogeneously computed accurate bolometric luminosities and effective temperatures of 1843 single stars, derived their radii and masses, studied the impact of metallicity, and compared our results with the literature. The over 40 000 individually inspected magnitudes, together with the basic data and derived parameters of the stars, individual and averaged by spectral type, have been made public to the astronomical community. In addition, we have reported 40 new close multiple systems and candidates (ρ < 3.3 arcsec) and 36 overluminous stars that are assigned to young Galactic populations. Conclusions. In the new era of exoplanet searches around M dwarfs via transit (e.g. TESS, PLATO) and radial velocity (e.g. CARMENES, NIRPS+HARPS), this work is of fundamental importance for stellar and therefore planetary parameter determination. © ESO 2020.
Acceso Abierto
CHEOPS observations of the HD 108236 planetary system: a fifth planet, improved ephemerides, and planetary radii
(EDP Sciences, 2021-02-19) Bonfanti, A.; Delrez, L.; Hooton, M. J.; Wilson, T. G.; Fossati, L.; Alibert, Y.; Hoyer, S.; Mustill, A. J.; Osborn, Hugh P.; Adibekyan, V.; Gandolfi, D.; Piazza, D.; Piotto, G.; Pollacco, D.; Ragazzoni, R.; Rando, N.; Ratti, F.; Rauer, H.; Ribas, I.; Rieder, M.; Rohlfs, R.; Safa, F.; Salatti, M.; Ségransan, D.; Simon, A. E.; Smith, A. M. S.; Sordet, Michael; Steller, M.; Thomas, N.; Tschentscher, M.; Van Eylen, V.; Viotto, V.; Walter, I.; Walton, N. A.; Wildi, F.; Wolter, D.; Salmon, S.; Sousa, S. G.; Tuson, A.; Van Grootel, V.; Cabrera, J.; Nascimbeni, V.; Maxted, P. F. L.; Barros, S. C. C.; Billot, N.; Bonfils, X.; Borsato, L.; Broeg, C.; Davies, M. B.; Deleuil, M.; Demangeon, O. D. S.; Fridlund, M.; Lacedelli, G.; Lendl, M.; Persson, Carina; Santos, Nuno C.; Scandariato, G.; Szabó, Gy. M.; Collier Cameron, A.; Udry, S.; Benz, W.; Beck, M.; Ehrenreich, D.; Fortier, A.; Isaak, K. G.; Queloz, D.; Alonso, R.; Asquier, J.; Bandy, T.; Bárczy, T.; Barrado, D.; Barragán, O.; Baumjohann, W.; Beck, T.; Bekkelien, A.; Bergomi, M.; Brandeker, A.; Busch, M. D.; Cessa, V.; Charnoz, S.; Chazelas, B.; Van Damme, C. C.; Demory, B. O.; Erikson, A.; Farinato, J.; Futyan, D.; García Muñoz, Antonio; Gillon, M.; Guedel, M.; Guterman, P.; Hasiba, J.; Heng, K.; Hernández, E.; Kiss, L.; Kuntzer, T.; Laskar, J.; Lecavelier des Etangs, A.; Lovis, C.; Magrin, D.; Malvasio, L.; Marafatto, L.; Michaelis, H.; Munari, M.; Olofsson, G.; Ottacher, H.; Ottensamer, R.; Pagano, I.; Pallé, E.; Peter, G.; Swiss Space Office (SSO); La Silla Observatory; Austrian Research Promotion Agency (FFG); European Research Council (ERC); Swiss National Science Foundation (SNSF); Agencia Estatal de Investigación (AEI); Generalitat de Catalunya; European Space Agency (ESA); Fundacao para a Ciencia e a Tecnologia (FCT); Belgian Federal Science Policy Office (BELSPO); Hungarian National Research, Development and Innovation Office (NKFIH); Istituto Nazionale di Astrofisica (INAF); Swedish National Infrastructure for Computing (SNIC); Bonfanti, A. [0000-0002-1916-5935]; Cameron, A. [0000-0002-8863-7828]; Santos, N. [0000-0003-4422-2919]; Mustill, A. J. [0000-0002-2086-3642]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. The detection of a super-Earth and three mini-Neptunes transiting the bright (V = 9.2 mag) star HD 108236 (also known as TOI-1233) was recently reported on the basis of TESS and ground-based light curves. Aims. We perform a first characterisation of the HD 108236 planetary system through high-precision CHEOPS photometry and improve the transit ephemerides and system parameters. Methods. We characterise the host star through spectroscopic analysis and derive the radius with the infrared flux method. We constrain the stellar mass and age by combining the results obtained from two sets of stellar evolutionary tracks. We analyse the available TESS light curves and one CHEOPS transit light curve for each known planet in the system. Results. We find that HD 108236 is a Sun-like star with R⋆ = 0.877 ± 0.008 R⊙, M⋆ = 0.869−0.048+0.050 M⊙, and an age of 6.7−5.1+4.0 Gyr. We report the serendipitous detection of an additional planet, HD 108236 f, in one of the CHEOPS light curves. For this planet, the combined analysis of the TESS and CHEOPS light curves leads to a tentative orbital period of about 29.5 days. From the light curve analysis, we obtain radii of 1.615 ± 0.051, 2.071 ± 0.052, 2.539−0.065+0.062, 3.083 ± 0.052, and 2.017−0.057+0.052 R⊕ for planets HD 108236 b to HD 108236 f, respectively. These values are in agreement with previous TESS-based estimates, but with an improved precision of about a factor of two. We perform a stability analysis of the system, concluding that the planetary orbits most likely have eccentricities smaller than 0.1. We also employ a planetary atmospheric evolution framework to constrain the masses of the five planets, concluding that HD 108236 b and HD 108236 c should have an Earth-like density, while the outer planets should host a low mean molecular weight envelope. Conclusions. The detection of the fifth planet makes HD 108236 the third system brighter than V = 10 mag to host more than four transiting planets. The longer time span enables us to significantly improve the orbital ephemerides such that the uncertainty on the transit times will be of the order of minutes for the years to come. A comparison of the results obtained from the TESS and CHEOPS light curves indicates that for a V ~ 9 mag solar-like star and a transit signal of ~500 ppm, one CHEOPS transit light curve ensures the same level of photometric precision as eight TESS transits combined, although this conclusion depends on the length and position of the gaps in the light curve.
Acceso Abierto
Detection and characterization of an ultra-dense sub-Neptunian planet orbiting the Sun-like star K2-292★
(EDP Sciences, 2019-03-14) Luque, R.; Nowak, G.; Pallé, E.; Dai, F.; Kaminski, A.; Nagel, E.; Hidalgo, D.; Bauer, F. F.; Lafarga, M.; Livingston, J.; Barragán, O.; Hirano, T.; Fridlund, M.; Gandolfi, D.; Justesen, A. B.; Hjorth, M.; Van Eylen, V.; Winn, J. N.; Esposito, M.; Morales, J. C.; Albrecht, S.; Alonso, R.; Amado, P. J.; Beck, P.; Caballero, J. A.; Cabrera, J.; Cochran, W. D.; Csizmadia, Sz.; Deeg, H.; Eigmuller, Ph.; Endl, M.; Erikson, A.; Fukui, A.; Grziwa, S.; Guenther, E. W.; Hatzes, Artie; Knudstrup, E.; Korth, J.; Lam, K. W. F.; Lund, M. N.; Mathur, S.; Montañés Rodríguez, P.; Narita, N.; Nespral, D.; Niraula, P.; Pätzold, M.; Persson, Carina; Prieto Arranz, J.; Quirrenbach, A.; Rauer, H.; Redfield, S.; Reiners, A.; Ribas, I.; Smith, A. M. S.; European Research Council (ERC); Ministerio de Economía y Competitividad (MINECO); Japan Society for the Promotion of Science (JSPS); Danish National Research Foundation (DNRF); Deutsche Forschungsgemeinschaft (DFG); Swedish National Space Agency (SNSA); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We present the discovery and characterization of a new transiting planet from Campaign 17 of the Kepler extended mission K2. The planet K2-292 b is a warm sub-Neptune on a 17 day orbit around a bright (V = 9.9 mag) solar-like G3 V star with a mass and radius of M⋆ = 1.00 ± 0.03 M⊙ and R⋆ = 1.09 ± 0.03 R⊙, respectively. We modeled simultaneously the K2 photometry and CARMENES spectroscopic data and derived a radius of Rp=2.63−0.10+0.12 R⊕ and mass of Mp=24.5−4.4+4.4 M⊕, yielding a mean density of ρp=7.4−1.5+1.6 g cm−3, which makes it one of the densest sub-Neptunian planets known to date. We also detected a linear trend in the radial velocities of K2-292 (γ˙RV = −0.40−0.07+0.07 m s−1 d−1) that suggests a long-period companion with a minimum mass on the order of 33 M⊕. If confirmed, it would support a formation scenario of K2-292 b by migration caused by Kozai-Lidov oscillations.
Acceso Abierto
Detection and Doppler monitoring of K2-285 (EPIC 246471491), a system of four transiting planets smaller than Neptune
(EDP Sciences, 2019-03-04) Pallé, E.; Nowak, G.; Luque, R.; Hidalgo, D.; Barragán, O.; Prieto Arranz, J.; Hirano, T.; Fridlund, M.; Gandolfi, D.; Livingston, J.; Dai, F.; Morales, J. C.; Lafarga, M.; Albrecht, S.; Alonso, R.; Amado, P. J.; Caballero, J. A.; Cabrera, J.; Cochran, W. D.; Csizmadia, Sz.; Deeg, H.; Eigmuller, Ph.; Endl, M.; Erikson, A.; Fukui, A.; Guenther, E. W.; Grziwa, S.; Hatzes, Artie; Korth, J.; Kürster, M.; Kuzuhara, M.; Montañés Rodríguez, P.; Murgas Alcaino, F.; Narita, N.; Nespral, D.; Pätzold, M.; Persson, Carina; Quirrenbach, A.; Rauer, H.; Redfield, S.; Reiners, A.; Ribas, I.; Smith, A. M. S.; Van Eylen, V.; Winn, J. N.; Zechmeister, M.; Agencia Estatal de Investigación (AEI); Japan Society for the Promotion of Science (JSPS); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. The Kepler extended mission, also known as K2, has provided the community with a wealth of planetary candidates that orbit stars typically much brighter than the targets of the original mission. These planet candidates are suitable for further spectroscopic follow-up and precise mass determinations, leading ultimately to the construction of empirical mass-radius diagrams. Particularly interesting is to constrain the properties of planets that are between Earth and Neptune in size, the most abundant type of planet orbiting Sun-like stars with periods of less than a few years. Aims. Among many other K2 candidates, we discovered a multi-planetary system around EPIC 246471491, referred to henceforth as K2-285, which contains four planets, ranging in size from twice the size of Earth to nearly the size of Neptune. We aim here at confirming their planetary nature and characterizing the properties of this system. Methods. We measure the mass of the planets of the K2-285 system by means of precise radial-velocity measurements using the CARMENES spectrograph and the HARPS-N spectrograph. Results. With our data we are able to determine the mass of the two inner planets of the system with a precision better than 15%, and place upper limits on the masses of the two outer planets. Conclusions. We find that K2-285b has a mass of Mb = 9.68−1.37+1.21 M⊕ and a radius of Rb = 2.59−0.06+0.06 R⊕, yielding a mean density of ρb = 3.07−0.45+0.45 g cm−3, while K2-285c has a mass of Mc = 15.68−2.13+2.28 M⊕, radius of Rc = 3.53−0.08+0.08 R⊕, and a mean density of ρc = 1.95−0.28+0.32 g cm−3. For K2-285d (Rd = 2.48−0.06+0.06 R⊕) and K2-285e (Re = 1.95−0.05+0.05 R⊕), the upper limits for the masses are 6.5 M⊕ and 10.7 M⊕, respectively. The system is thus composed of an (almost) Neptune-twin planet (in mass and radius), two sub-Neptunes with very different densities and presumably bulk composition, and a fourth planet in the outermost orbit that resides right in the middle of the super-Earth/sub-Neptune radius gap. Future comparative planetology studies of this system would provide useful insights into planetary formation, and also a good test of atmospheric escape and evolution theories.
Acceso Abierto
Detection of the hydrogen Balmer lines in the ultra-hot Jupiter WASP-33b
(EDP Sciences, 2021-01-15) Yan, F.; Wyttenbach, A.; Casasayas Barris, N.; Reiners, A.; Pallé, E.; Henning, T.; Molière, P.; Czesla, S.; Nortmann, L.; Molaverdikhani, K.; Chen, G.; Snellen, Ignas; Zechmeister, M.; Huang, C. X.; Ribas, I.; Quirrenbach, A.; Caballero, J. A.; Amado, P. J.; Cont, D.; Khalafinejad, S.; Khaimova, J.; López Puertas, M.; Montes, D.; Nagel, E.; Oshagh, M.; Pedraz, S.; Stangret, M.; Deutsche Forschungsgemeinschaft (DFG); Agencia Estatal de Investigación (AEI); Generalitat de Catalunya; Ministerio de Economía y Competitividad (MINECO); Max-Planck-Gesellschaft (MPG); European Research Council (ERC); Swiss National Science Foundation (SNSF); 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
Ultra-hot Jupiters (UHJs) are highly irradiated giant exoplanets with extremely high day-side temperatures, which lead to thermal dissociation of most molecular species. It is expected that the neutral hydrogen atom is one of the main species in the upper atmospheres of UHJs. Neutral hydrogen has been detected in several UHJs by observing their Balmer line absorption. In this work, we report four transit observations of the UHJ WASP-33b, performed with the CARMENES and HARPS-North spectrographs, and the detection of the Hα, Hβ, and Hγ lines in the planetary transmission spectrum. The combined Hα transmission spectrum of the four transits has an absorption depth of 0.99 ± 0.05%, which corresponds to an effective radius of 1.31 ± 0.01 Rp. The strong Hα absorption indicates that the line probes the high-altitude thermosphere. We further fitted the three Balmer lines using the PAWN model, assuming that the atmosphere is hydrodynamic and in local thermodynamic equilibrium. We retrieved a thermosphere temperature 12 200−1000+1300 K and a mass-loss rate Ṁ = 1011.8−0.5+0.6 g s−1. The retrieved high mass-loss rate is compatible with the “Balmer-driven” atmospheric escape scenario, in which the stellar Balmer continua radiation in the near-ultraviolet is substantially absorbed by excited hydrogen atoms in the planetary thermosphere.
Acceso Abierto
Discriminating between hazy and clear hot-Jupiter atmospheres with CARMENES.
(EDP Sciences, 2020-10-27) Sánchez López, A.; López Puertas, M.; Snellen, Ignas; Nagel, E.; Bauer, F. F.; Pallé, E.; Tal Or, L.; Amado, P. J.; Caballero, P. J.; Czesla, S.; Nortmann, L.; Reiners, A.; Ribas, I.; Quirrenbach, A.; Aceituno, J.; Béjar, V. J. S.; Casasayas Barris, N.; Henning, T.; Molaverdikhani, K.; Montes, D.; Stangret, M.; Zapatero Osorio, M. R.; Zechmeister, M.; European Research Council (ERC); Deutsche Forschungsgemeinschaft (DFG); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Ministerio de Ciencia e Innovación (MICINN); Pallé, E. [0000-0003-0987-1593]; Sánchez López, A. [0000-0002-0516-7956]; Nagel, E. [0000-0002-4019-3631]; Montes, D. [0000-0002-7779-238X]; Molaverdikhani, K. [0000-0002-0502-0428]; López Puertas, M. [0000-0003-2941-7734]; Snellen, I. A. G. [0000-0003-1624-3667]; Centro de Excelencia Científica Severo Ochoa Instituto de Astrofísica de Andalucía CSIC, 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. Relatively large radii of some hot Jupiters observed in the ultraviolet and blue-optical are generally interpreted to be due to Rayleigh scattering by high-altitude haze particles. However, the haze composition and its production mechanisms are not fully understood, and observational information is still limited. Aims. We aim to study the presence of hazes in the atmospheres of HD 209458 b and HD 189733 b with high spectral resolution spectra by analysing the strength of water vapour cross-correlation signals across the red optical and near-infrared wavelength ranges. Methods. A total of seven transits of the two planets were observed with the CARMENES spectrograph at the 3.5 m Calar Alto telescope. Their Doppler-shifted signals were disentangled from the telluric and stellar contributions using the detrending algorithm SYSREM. The residual spectra were subsequently cross-correlated with water vapour templates at 0.70–0.96 μm to measure the strength of the water vapour absorption bands. Results. The optical water vapour bands were detected at 5.2σ in HD 209458 b in one transit, whereas no evidence of them was found in four transits of HD 189733 b. Therefore, the relative strength of the optical water bands compared to those in the near-infrared were found to be larger in HD 209458 b than in HD 189733 b. Conclusions. We interpret the non-detection of optical water bands in the transmission spectra of HD 189733 b, compared to the detection in HD 209458 b, to be due to the presence of high-altitude hazes in the former planet, which are largely absent in the latter. This is consistent with previous measurements with the Hubble Space Telescope. We show that currently available CARMENES observations of hot Jupiters can be used to investigate the presence of haze extinction in their atmospheres.
Acceso Abierto
Evidence of energy-, recombination-, and photon-limited escape regimes in giant planet H/He atmospheres
(EDP Sciences, 2021-04-23) Lampón, M.; López Puertas, M.; Czesla, S.; Sánchez López, A.; Lara, L. M.; Salz, M.; Sanz Forcada, J.; Molaverdikhani, K.; Quirrenbach, A.; Pallé, E.; Caballero, J. A.; Henning, T.; Nortmann, L.; Amado, P. J.; Montes, D.; Reiners, A.; Ribas, I.; Consejo Superior de Investigaciones Científicas (CSIC); Junta de Andalucía; European Regional Development Fund (ERDF); Deutsche Forschungsgemeinschaft (DFG); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Generalitat de Catalunya; European Research Council (ERC); Lampón, M. [0000-0002-0183-7158]; López Puertas, M. [0000-0003-2941-7734]; Sánchez López, A. [0000-0002-0516-7956]; Lara, L. M. [0000-0002-7184-920X]; Sanz Forcada, J. [0000-0002-1600-7835]; Molaverdikhani, K. [0000-0002-0502-0428]; Caballero, J. A. [0000-0002-7349-1387]; Nortmann, L. [0000-0001-8419-8760]; Amado, P. J. [0000-0001-8012-3788]; Montes, D. [0000-0002-7779-238X]; Ribas, I. [0000-0002-6689-0312]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Centro de Excelencia Científica Severo Ochoa Instituto de Astrofísica de Andalucía , SEV-2017-0709; Centro de Excelencia Científica Severo Ochoa Instituto de Astrofísica de Canarias, SEV-2015-0548
Hydrodynamic escape is the most efficient atmospheric mechanism of planetary mass loss and has a large impact on planetary evolution. Three hydrodynamic escape regimes have been identified theoretically: energy-limited, recombination-limited, and photon-limited. However, no evidence of these regimes had been reported until now. Here, we report evidence of these three regimes via an analysis of a helium I triplet at 10 830 Å and Lyα absorption involving a 1D hydrodynamic model that allows us to estimate hydrogen recombination and advection rates. In particular, we show that HD 209458 b is in the energy-limited regime, HD 189733 b is in the recombination-limited regime, and GJ 3470 b is in the photon-limited regime. These exoplanets can be considered as benchmark cases for their respective regimes.
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
He I λ 10 830 Å in the transmission spectrum of HD209458 b
(EDP Sciences, 2019-09-12) Alonso Floriano, F. J.; Snellen, Ignas; Czesla, S.; Bauer, F. F.; Salz, M.; Lampón, M.; Lara, L. M.; Nagel, E.; López Puertas, M.; Nortmann, L.; Sánchez López, A.; Sanz Forcada, J.; Caballero, J. A.; Reiners, A.; Ribas, I.; Quirrenbach, A.; Amado, P. J.; Aceituno, J.; Anglada Escudé, G.; Béjar, V. J. S.; Brinkmöller, M.; Hatzes, Artie; Henning, T.; Kaminski, A.; Kürster, M.; Labarga, F.; Montes, D.; Pallé, E.; Schmitt, J. H. M. M.; Zapatero Osorio, M. R.; Ministerio de Economía y Competitividad (MINECO); Max-Planck-Gesellschaft (MPG); European Research Council (ERC); Comunidad de Madrid; Agencia Estatal de Investigación (AEI); Alonso Floriano, F. J. [0000-0003-1202-5734]; 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
Context. Recently, the He I triplet at 10 830 Å was rediscovered as an excellent probe of the extended and possibly evaporating atmospheres of close-in transiting planets. This has already resulted in detections of this triplet in the atmospheres of a handful of planets, both from space and from the ground. However, while a strong signal is expected for the hot Jupiter HD 209458 b, only upper limits have been obtained so far. Aims. Our goal is to measure the helium excess absorption from HD 209458 b and assess the extended atmosphere of the planet and possible evaporation. Methods. We obtained new high-resolution spectral transit time-series of HD 209458 b using CARMENES at the 3.5 m Calar Alto telescope, targeting the He I triplet at 10 830 Å at a spectral resolving power of 80 400. The observed spectra were corrected for stellar absorption lines using out-of-transit data, for telluric absorption using the MOLECFIT software, and for the sky emission lines using simultaneous sky measurements through a second fibre. Results. We detect He I absorption at a level of 0.91 ± 0.10% (9 σ) at mid-transit. The absorption follows the radial velocity change of the planet during transit, unambiguously identifying the planet as the source of the absorption. The core of the absorption exhibits a net blueshift of 1.8 ± 1.3 km s−1. Possible low-level excess absorption is seen further blueward from the main absorption near the centre of the transit, which could be caused by an extended tail. However, this needs to be confirmed. Conclusions. Our results further support a close relation between the strength of planetary absorption in the helium triplet lines and the level of ionising, stellar X-ray, and extreme-UV irradiation.
Acceso Abierto
Ionized calcium in the atmospheres of two ultra-hot exoplanets WASP-33b and KELT-9b
(EDP Sciences, 2019-12-05) Yan, F.; Casasayas Barris, N.; Molaverdikhani, K.; Alonso Floriano, F. J.; Reiners, A.; Pallé, E.; Henning, T.; Mollière, P.; Chen, G.; Nortmann, L.; Snellen, Ignas; Ribas, I.; Quirrenbach, A.; Caballero, J. A.; Amado, P. J.; Azzaro, M.; Bauer, F. F.; Cortés Contreras, M.; Czesla, S.; Khalafinejad, S.; Lara, L. M.; López Puertas, M.; Montes, D.; Nagel, E.; Oshagh, M.; Sánchez López, A.; Strangret, M.; Zechmeister, M.; European Research Council (ERC); Deutsche Forschungsgemeinschaft (DFG); Chen, G. [0000-0003-0740-5433]; Ribas, I. [0000-0002-6689-0312]; Montes, D. [0000-0002-7779-238X]; Yan, F. [0000-0001-9585-9034]; Molaverdikhani, K. [0000-0002-0502-0428]; Molliere, P. [0000-0003-4096-7067]; Lara, L. M. [0000-0002-7184-920X]; Nagel, E. [0000-0002-4019-3631]; Amado, P. J. [0000-0002-8388-6040]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Ultra-hot Jupiters are emerging as a new class of exoplanets. Studying their chemical compositions and temperature structures will improve our understanding of their mass loss rate as well as their formation and evolution. We present the detection of ionized calcium in the two hottest giant exoplanets - KELT-9b and WASP-33b. By using transit datasets from CARMENES and HARPS-N observations, we achieved high-confidence-level detections of Ca II using the cross-correlation method. We further obtain the transmission spectra around the individual lines of the Ca II H&K doublet and the near-infrared triplet, and measure their line profiles. The Ca II H&K lines have an average line depth of 2.02 +/- 0.17% (effective radius of 1.56 R-p) for WASP-33b and an average line depth of 0.78 +/- 0.04% (effective radius of 1.47 R-p) for KELT-9b, which indicates that the absorptions are from very high upper-atmosphere layers close to the planetary Roche lobes. The observed Ca II lines are significantly deeper than the predicted values from the hydrostatic models. Such a discrepancy is probably a result of hydrodynamic outflow that transports a significant amount of Ca II into the upper atmosphere. The prominent Ca II detection with the lack of significant Ca I detection implies that calcium is mostly ionized in the upper atmospheres of the two planets.
Acceso Abierto
Is there Na i in the atmosphere of HD 209458b?: Effect of the centre-to-limb variation and Rossiter-McLaughlin effect in transmission spectroscopy studies
(EDP Sciences, 2020-04-03) Casasayas Barris, N.; Pallé, E.; Yan, F.; Chen, G.; Luque, R.; Strangret, M.; Nagel, E.; Zechmeister, M.; Oshagh, M.; Sanz Forcada, J.; Nortmann, L.; Alonso Floriano, F. J.; Molaverdikhani, K.; Montes, D.; Quirrenbach, A.; Reiners, A.; Ribas, I.; Sánchez López, A.; Zapatero Osorio, M. R.; Deutsche Forschungsgemeinschaft (DFG); Agencia Estatal de Investigación (AEI); Junta de Andalucía; National Natural Science Foundation of China (NSFC); 0000-0002-2891-8222; 0000-0003-0987-1593; 0000-0001-6470-2907; 0000-0001-5664-2852; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
HD 209458b was the first transiting planet discovered, and the first for which an atmosphere, in particular Na I, was detected. With time, it has become one of the most frequently studied planets, with a large diversity of atmospheric studies using low- and high-resolution spectroscopy. Here, we present transit spectroscopy observations of HD 209458b using the HARPS-N and CARMENES spectrographs. We fit the Rossiter-McLaughlin effect by combining radial velocity data from both instruments (nine transits in total), measuring a projected spin-orbit angle of - 1.6 ± 0.3 deg. We also present the analysis of high-resolution transmission spectroscopy around the Na I region at 590 nm, using a total of five transit observations. In contrast to previous studies where atmospheric Na I absorption is detected, we find that for all of the nights, whether individually or combined, the transmission spectra can be explained by the combination of the centre-to-limb variation and the Rossiter-McLaughlin effect. This is also observed in the time-evolution maps and transmission light curves, but at lower signal-to-noise ratio. Other strong lines such as Hα, Ca II IRT, the Mg I triplet region, and K I D1 are analysed, and are also consistent with the modelled effects, without considering any contribution from the exoplanet atmosphere. Thus, the transmission spectrum reveals no detectable Na I absorption in HD 209458b. We discuss how previous pioneering studies of this benchmark object may have overlooked these effects. While for some star-planet systems these effects are small, for other planetary atmospheres the results reported in the literature may require revision. © ESO 2020.
Acceso Abierto
Magnetic fields in M dwarfs from the CARMENES survey
(EDP Sciences, 2019-06-18) Shulyak, D.; Reiners, A.; Nagel, E.; Tal Or, L.; Caballero, J. A.; Zechmeister, M.; Béjar, V. J. S.; Cortés Contreras, M.; Martín, Eduardo L.; Kaminski, A.; Ribas, I.; Quirrenbach, A.; Amado, P. J.; Anglada Escudé, G.; Bauer, F. F.; Dreizler, S.; Guenther, E. W.; Henning, T.; Jeffers, S. V.; Kürster, M.; Lafarga, M.; Montes, D.; Morales, J. C.; Pedraz, S.; Israel Science Foundation (ISF); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. M dwarfs are known to generate the strongest magnetic fields among main-sequence stars with convective envelopes, but we are still lacking a consistent picture of the link between the magnetic fields and underlying dynamo mechanisms, rotation, and activity. Aims. In this work we aim to measure magnetic fields from the high-resolution near-infrared spectra taken with the CARMENES radial-velocity planet survey in a sample of 29 active M dwarfs and compare our results against stellar parameters. Methods. We used the state-of-the-art radiative transfer code to measure total magnetic flux densities from the Zeeman broadening of spectral lines and filling factors. Results. We detect strong kG magnetic fields in all our targets. In 16 stars the magnetic fields were measured for the first time. Our measurements are consistent with the magnetic field saturation in stars with rotation periods P < 4 d. The analysis of the magnetic filling factors reveal two different patterns of either very smooth distribution or a more patchy one, which can be connected to the dynamo state of the stars and/or stellar mass. Conclusions. Our measurements extend the list of M dwarfs with strong surface magnetic fields. They also allow us to better constrain the interplay between the magnetic energy, stellar rotation, and underlying dynamo action. The high spectral resolution and observations at near-infrared wavelengths are the beneficial capabilities of the CARMENES instrument that allow us to address important questions about the stellar magnetism.
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, Artie; 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, Richard; Omiya, M.; Pedraz, S.; Passegger, V. M.; Rackham, B. V.; Rudat, A.; Schlieder, Joshua; 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.