Astronomy & Astrophysics最新文献

{"title":"The CARMENES search for exoplanets around M dwarfs","authors":"M. Lafarga, I. Ribas, C. Lovis, M. Perger, M. Zechmeister, F. Bauer, M. Kürster, M. Cortés-Contreras, J. C. Morales, E. Herrero, A. Rosich, D. Baroch, A. Reiners, J. A. Caballero, A. Quirrenbach, P. Amado, J. M. Alacid, V. Béjar, S. Dreizler, A. Hatzes, T. Henning, S. Jeffers, A. Kaminski, D. Montes, S. Pedraz, C. Rodríguez-López, J. H. M. M. Schmitt","doi":"10.1051/0004-6361/201937222","DOIUrl":"https://doi.org/10.1051/0004-6361/201937222","url":null,"abstract":"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.\u0000Aims. 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.\u0000Methods. 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.\u0000Results. 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.","PeriodicalId":48759,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2020-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141222538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The CARMENES search for exoplanets around M dwarfs","authors":"G. Nowak, R. Luque, H. Parviainen, E. Pallé, K. Molaverdikhani, V. Béjar, J. Lillo-Box, C. Rodríguez-López, J. A. Caballero, M. Zechmeister, V. Passegger, C. Cifuentes, A. Schweitzer, N. Narita, B. Cale, N. Espinoza, F. Murgas, D. Hidalgo, M. R. Z. Osorio, F. Pozuelos, F. Aceituno, P. Amado, K. Barkaoui, D. Barrado, F. Bauer, Z. Benkhaldoun, D. Caldwell, N. C. Barris, P. Chaturvedi, Guo-qing Chen, K. Collins, K. Collins, M. Cortés-Contreras, I. Crossfield, J. D. Leon, E. D. Alonso, S. Dreizler, M. E. Mufti, E. Esparza-Borges, Z. Essack, A. Fukui, E. Gaidos, M. Gillon, E. Gonzales, P. Guerra, A. Hatzes, T. Henning, E. Herrero, K. Hesse, T. Hirano, S. Howell, S. Jeffers, E. Jehin, J. Jenkins, A. Kaminski, J. Kemmer, J. Kielkopf, D. Kossakowski, T. Kotani, M. Kürster, M. Lafarga, D. Latham, Nicholas Law, Jack J. Lissauer, N. Lodieu, A. Madrigal-Aguado, A. Mann, B. Massey, R. Matson, E. Matthews, P. Montañés-Rodríguez, D. Montes, J. C. Morales, M. Mori, E. Nagel, M. Oshagh, S. Pedraz, P. Plavchan, D. Pollacco","doi":"10.1051/0004-6361/202037867","DOIUrl":"https://doi.org/10.1051/0004-6361/202037867","url":null,"abstract":"We present the discovery and characterisation of two transiting planets observed by the Transiting Exoplanet Survey Satellite (TESS) orbiting the nearby (d⋆ ≈ 22 pc), bright (J ≈ 9 mag) M3.5 dwarf LTT 3780 (TOI–732). We confirm both planets and their association with LTT 3780 via ground-based photometry and determine their masses using precise radial velocities measured with the CARMENES spectrograph. Precise stellar parameters determined from CARMENES high-resolution spectra confirm that LTT 3780 is a mid-M dwarf with an effective temperature of Teff = 3360 ± 51 K, a surface gravity of log g⋆ = 4.81 ± 0.04 (cgs), and an iron abundance of [Fe/H] = 0.09 ± 0.16 dex, with an inferred mass of M⋆ = 0.379 ± 0.016M⊙ and a radius of R⋆ = 0.382 ± 0.012R⊙. The ultra-short-period planet LTT 3780 b (Pb = 0.77 d) with a radius of 1.35−0.06+0.06 R⊕, a mass of 2.34−0.23+0.24 M⊕, and a bulk density of 5.24−0.81+0.94 g cm−3 joins the population of Earth-size planets with rocky, terrestrial composition. The outer planet, LTT 3780 c, with an orbital period of 12.25 d, radius of 2.42−0.10+0.10 R⊕, mass of 6.29−0.61+0.63 M⊕, and mean density of 2.45−0.37+0.44 g cm−3 belongs to the population of dense sub-Neptunes. With the two planets located on opposite sides of the radius gap, this planetary system is anexcellent target for testing planetary formation, evolution, and atmospheric models. In particular, LTT 3780 c is an ideal object for atmospheric studies with the James Webb Space Telescope (JWST).","PeriodicalId":48759,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2020-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141226397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The CARMENES search for exoplanets around M dwarfs","authors":"E. González-Álvarez, M. R. Z. Osorio, J. A. Caballero, J. Sanz-Forcada, V. Béjar, L. González-Cuesta, S. Dreizler, F. Bauer, E. Rodríguez, L. Tal-Or, M. Zechmeister, D. Montes, M. J. López-González, I. Ribas, A. Reiners, A. Quirrenbach, P. Amado, G. Anglada-Escudé, M. Azzaro, M. Cortés-Contreras, A. Hatzes, T. Henning, S. Jeffers, A. Kaminski, M. Kürster, M. Lafarga, J. C. Morales, E. Pallé, M. Perger, J. H. M. M. Schmitt","doi":"10.1051/0004-6361/201937050","DOIUrl":"https://doi.org/10.1051/0004-6361/201937050","url":null,"abstract":"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.\u0000Methods. 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.\u0000Results. 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.\u0000Conclusions. 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.","PeriodicalId":48759,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2020-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141225608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revealing the structure of the outer disks of Be stars (Corrigendum)","authors":"R. Klement, A. Carciofi, T. Rivinius, L. D. Matthews, R. G. Vieira, R. Ignace, J. E. Bjorkman, B. Mota, D. Faes, A. Bratcher, M. Curé, S. Štefl","doi":"10.1051/0004-6361/201629932e","DOIUrl":"https://doi.org/10.1051/0004-6361/201629932e","url":null,"abstract":"1 European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla 19001 Santiago, Chile e-mail: robertklement@gmail.com 2 Astronomical Institute of Charles University, Charles University, V Holešovičkách 2, 180 00 Prague 8, Troja, Czech Republic 3 Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, Rua do Matão 1226, Cidade Universitária, 05508-090 São Paulo, SP, Brazil 4 MIT Haystack Observatory, off Route 40, Westford, MA 01886, USA 5 Department of Physics & Astronomy, East Tennessee State University, Box 70652, Johnson City, TN 37614, USA 6 Ritter Observatory, Department of Physics & Astronomy, University of Toledo, Toledo, OH 43606, USA 7 Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Casilla 5030 Valparaíso, Chile","PeriodicalId":48759,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2020-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141225658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transiting exoplanets from the CoRoT space mission","authors":"P. Bordé, R. F. Díaz, O. Creevey, C. Damiani, H. Deeg, P. Klagyivik, G. Wuchterl, D. Gandolfi, M. Fridlund, F. Bouchy, S. Aigrain, R. Alonso, J. Almenara, A. Baglin, S. Barros, A. Bonomo, J. Cabrera, S. Csizmadia, M. Deleuil, A. Erikson, S. Ferraz-Mello, E. Guenther, T. Guillot, S. Grziwa, A. Hatzes, G. Hébrard, T. Mazeh, M. Ollivier, H. Parviainen, M. Pätzold, H. Rauer, D. Rouan, A. Santerne, J. Schneider","doi":"10.1051/0004-6361/201732393","DOIUrl":"https://doi.org/10.1051/0004-6361/201732393","url":null,"abstract":"Aims. We report the discovery as well as the orbital and physical characterizations of two new transiting giant exoplanets, CoRoT-30 b and CoRoT-31 b, with the CoRoT space telescope.\u0000Methods. We analyzed two complementary data sets: photometric transit light curves measured by CoRoT, and radial velocity curves measured by the HARPS spectrometer. To derive the absolute masses and radii of the planets, we modeled the stars from available magnitudes and spectra.\u0000Results. We find that CoRoT-30 b is a warm Jupiter on a close-to-circular 9.06-day orbit around a G3V star with a semi-major axis of about 0.08 AU. It has a radius of 1.01 ± 0.08 RJ, a mass of 2.90 ± 0.22 MJ, and therefore a mean density of 3.45 ± 0.65 g cm−3. The hot Jupiter CoRoT-31 b is on a close-to-circular 4.63-day orbit around a G2 IV star with a semi-major axis of about 0.05 AU. It has a radius of 1.46 ± 0.30 RJ, a mass of 0.84 ± 0.34 MJ, and therefore a mean density of 0.33 ± 0.18 g cm−3.\u0000Conclusions. Neither system seems to support the claim that stars hosting planets are more depleted in lithium. The radii of both planets are close to that of Jupiter, but they differ in mass; CoRoT-30 b is ten times denser than CoRoT-31 b. The core of CoRoT-30 b would weigh between 15 and 75 Earth masses, whereas relatively weak constraints favor no core for CoRoT-31 b. In terms of evolution, the characteristics of CoRoT-31 b appear to be compatible with the high-eccentricity migration scenario, which is not the case for CoRoT-30 b. The angular momentum of CoRoT-31 b is currently too low for the planet to evolve toward synchronization of its orbital revolution with stellar rotation, and the planet will slowly spiral-in while its host star becomes a red giant. CoRoT-30 b is not synchronized either: it looses angular momentum owing to stellar winds and is expected reach steady state in about 2 Gyr. CoRoT-30 and 31, as a pair, are a truly remarkable example of diversity in systems with hot Jupiters.","PeriodicalId":48759,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2020-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141226296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}