Examinando por Autor "Bauer, F. F."

Mostrando 1 - 16 de 16

Acceso Abierto
Discriminating between hazy and clear hot-Jupiter atmospheres with CARMENES.
(EDP Sciences, 2020-10-27) Sánchez López, A.; López Puertas, M.; Snellen, I. A. G.; 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
He I λ 10 830 Å in the transmission spectrum of HD209458 b
(EDP Sciences, 2019-09-12) Alonso Floriano, F. J.; Snellen, I. A. G.; 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, A. P.; 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, I. A. G.; 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
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, E. 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
Modelling the He i triplet absorption at 10 830 A in the atmosphere of HD 209458 b
(EDP Sciences, 2020-04-07) Lampón, M.; López Puertas, M.; Lara, L. M.; Sánchez López, A.; Salz, M.; Czesla, S.; Sanz Forcada, J.; Molaverdikhani, K.; Alonso Floriano, F. J.; Nortmann, L.; Caballero, J. A.; Bauer, F. F.; Pallé, E.; Montes, D.; Quirrenbach, A.; Nagel, E.; Ribas, I.; Reiners, A.; Amado, P. J.; Deutsche Forschungsgemeinschaft (DFG); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Junta de Andalucía; 0000-0002-0183-7158; 0000-0003-2941-7734; 0000-0002-7184-920X; 0000-0002-0516-7956; 0000-0002-0502-0428; 0000-0002-7349-1387; 0000-0003-1212-5225; 0000-0003-0987-1593; 0000-0002-7779-238X; 0000-0002-4019-3631; 0000-0002-6689-0312; 0000-0002-8388-6040; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709
Context. HD 209458 b is an exoplanet with an upper atmosphere undergoing blow-off escape that has mainly been studied using measurements of the Lyα absorption. Recently, high-resolution measurements of absorption in the He I triplet line at 10 830 A of several exoplanets (including HD 209458 b) have been reported, creating a new opportunity to probe escaping atmospheres. Aims. We aim to better understand the atmospheric regions of HD 209458 b from where the escape originates. Methods. We developed a 1D hydrodynamic model with spherical symmetry for the HD 209458 b thermosphere coupled with a non-local thermodynamic model for the population of the He I triplet state. In addition, we performed high-resolution radiative transfer calculations of synthetic spectra for the helium triplet lines and compared them with the measured absorption spectrum in order to retrieve information about the atmospheric parameters. Results. We find that the measured spectrum constrains the [H]/[H+] transition altitude occurring in the range of 1.2 RP-1.9 RP. Hydrogen is almost fully ionised at altitudes above 2.9 RP. We also find that the X-ray and extreme ultraviolet absorption takes place at effective radii from 1.16 to 1.30 RP, and that the He I triplet peak density occurs at altitudes from 1.04 to 1.60 RP. Additionally, the averaged mean molecular weight is confined to the 0.61-0.73 g mole-1 interval, and the thermospheric H/He ratio should be larger than 90/10, and most likely approximately 98/2. We also provide a one-to-one relationship between mass-loss rate and temperature. Based on the energy-limited escape approach and assuming heating efficiencies of 0.1-0.2, we find a mass-loss rate in the range of (0.42-1.00) ×1011 g s-1 and a corresponding temperature range of 7125-8125 K. Conclusions. The analysis of the measured He I triplet absorption spectrum significantly constrains the thermospheric structure of HD 209458 b and advances our knowledge of its escaping atmosphere. © ESO 2020.
Acceso Abierto
Modelling the He I triplet absorption at 10 830 Å in the atmospheres of HD 189733 b and GJ 3470 b
(EDP Sciences, 2021-03-23) Lampón, M.; López Puertas, M.; Sanz Forcada, J.; Sánchez López, A.; Molaverdikhani, K.; Czesla, S.; Quirrenbach, A.; Pallé, E.; Caballero, J. A.; Henning, T.; Salz, M.; Nortmann, L.; Aceituno, J.; Amado, P. J.; Bauer, F. F.; Montes, D.; Nagel, E.; Reiners, A.; Ribas, I.; European Regional Development Fund (ERDF); Deutsche Forschungsgemeinschaft (DFG); Agencia Estatal de Investigación (AEI); Generalitat de Catalunya; European Research Council (ERC); 0000-0002-0183-7158; 0000-0003-2941-7734; 0000-0002-1600-7835; 0000-0002-0516-7956; 0000-0002-7349-1387; 0000-0001-8419-8760; 0000-0001-8012-3788; 0000-0002-4019-3631; 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; 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
Characterising the atmospheres of exoplanets is key to understanding their nature and provides hints about their formation and evolution. High resolution measurements of the helium triplet absorption of highly irradiated planets have been recently reported, which provide a new means of studying their atmospheric escape. In this work we study the escape of the upper atmospheres of HD 189733 b and GJ 3470 b by analysing high resolution He I triplet absorption measurements and using a 1D hydrodynamic spherically symmetric model coupled with a non-local thermodynamic model for the He I triplet state. We also use the H density derived from Lyα observations to further constrain their temperatures, mass-loss rates, and H/He ratios. We have significantly improved our knowledge of the upper atmospheres of these planets. While HD 189733 b has a rather compressed atmosphere and small gas radial velocities, GJ 3470 b, on the other hand with a gravitational potential ten times smaller, exhibits a very extended atmosphere and large radial outflow velocities. Hence, although GJ 3470 b is much less irradiated in the X-ray and extreme ultraviolet radiation, and its upper atmosphere is much cooler, it evaporates at a comparable rate. In particular, we find that the upper atmosphere of HD 189733 b is compact and hot, with a maximum temperature of 12 400−300+400 K, with a very low mean molecular mass (H/He = (99.2/0.8) ± 0.1), which is almost fully ionised above 1.1 RP, and with a mass-loss rate of (1.1 ± 0.1) × 1011 g s−1. In contrast, the upper atmosphere of GJ 3470 b is highly extended and relatively cold, with a maximum temperature of 5100 ± 900 K, also with a very low mean molecular mass (H/He = (98.5/1.5)−1.5+1.0), which is not strongly ionised, and with a mass-loss rate of (1.9 ± 1.1) × 1011 g s−1. Furthermore, our results suggest that upper atmospheres of giant planets undergoing hydrodynamic escape tend to have a very low mean molecular mass (H/He ≳ 97/3).
Acceso Abierto
Multiple water band detections in the CARMENES near-infrared transmission spectrum of HD 189733 b
(EDP Sciences, 2019-01-10) Alonso Floriano, F. J.; Sánchez López, A.; Snellen, I. A. G.; López Puertas, M.; Nagel, E.; Amado, P. J.; Bauer, F. F.; Caballero, J. A.; Czesla, S.; Nortmann, L.; Pallé, E.; Salz, M.; Reiners, A.; Ribas, I.; Quirrenbach, A.; Aceituno, J.; Anglada Escudé, G.; Béjar, V. J. S.; Guenther, E. W.; Henning, T.; Kaminski, A.; Kürster, M.; Lampón, M.; Lara, L. M.; Montes, D.; Morales, J. C.; Tal Or, L.; Schmitt, J. H. M. M.; Zapatero Osorio, M. R.; Zechmeister, M.; European Research Council (ERC); Ministerio de Economía y Competitividad (MINECO); Ministerio de Ciencia e Innovación (MICINN); Agencia Estatal de Investigación (AEI); Zapatero Osorio, M. R. [0000-0001-5664-2852]; 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
Aims. We explore the capabilities of CARMENES for characterising hot-Jupiter atmospheres by targeting multiple water bands, in particular, those at 1.15 and 1.4 μm. Hubble Space Telescope observations suggest that this wavelength region is relevant for distinguishing between hazy and/or cloudy and clear atmospheres. Methods. We observed one transit of the hot Jupiter HD 189733 b with CARMENES. Telluric and stellar absorption lines were removed using SYSREM, which performs a principal component analysis including proper error propagation. The residual spectra were analysed for water absorption with cross-correlation techniques using synthetic atmospheric absorption models. Results. We report a cross-correlation peak at a signal-to-noise ratio (S/N) of 6.6, revealing the presence of water in the transmission spectrum of HD 189733 b. The absorption signal appeared slightly blueshifted at –3.9 ± 1.3 km s−1. We measured the individual cross-correlation signals of the water bands at 1.15 and 1.4 μm, finding cross-correlation peaks at S/N of 4.9 and 4.4, respectively. The 1.4 μm feature is consistent with that observed with the Hubble Space Telescope. Conclusions. The water bands studied in this work have been mainly observed in a handful of planets from space. Being able also to detect them individually from the ground at higher spectral resolution can provide insightful information to constrain the properties of exoplanet atmospheres. Although the current multi-band detections can not yet constrain atmospheric haze models for HD 189733 b, future observations at higher S/N could provide an alternative way to achieve this aim.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs Convective shift and starspot constraints from chromatic radial velocities
(EDP Sciences, 2020-09-10) Baroch, D.; Morales, J. C.; Ribas, I.; Herrero, E.; Rosich, A.; Perger, M.; Anglada Escudé, G.; Reiners, A.; Caballero, J. A.; Quirrenbach, A.; Amado, P. J.; Jeffers, S. V.; Cifuentes, C.; Passegger, V. M.; Schweitzer, A.; Lafarga, M.; Bauer, F. F.; Béjar, V. J. S.; Colomé, J.; Cortés Contreras, M.; Dreizler, S.; Galadí Enríquez, D.; Hatzes, A. P.; Henning, T.; Kaminski, A.; Kürster, M.; Montes, D.; Rodríguez López, C.; Zechmeister, M.; Deutsche Forschungsgemeinschaft (DFG); Agencia Estatal de Investigación (AEI); National Aeronautics and Space Administration (NASA); Baroch, D. [0000-0001-7568-5161]; Ribas, I. [0000-0002-6689-0312]; Montes, D. [0000-0002-7779-238X]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709
Context. Variability caused by stellar activity represents a challenge to the discovery and characterization of terrestrial exoplanets and complicates the interpretation of atmospheric planetary signals. Aims. We aim to use a detailed modeling tool to reproduce the effect of active regions on radial velocity measurements, which aids the identification of the key parameters that have an impact on the induced variability. Methods. We analyzed the effect of stellar activity on radial velocities as a function of wavelength by simulating the impact of the properties of spots, shifts induced by convective motions, and rotation. We focused our modeling effort on the active star YZ CMi (GJ 285), which was photometrically and spectroscopically monitored with CARMENES and the Telescopi Joan Oró. Results. We demonstrate that radial velocity curves at different wavelengths yield determinations of key properties of active regions, including spot-filling factor, temperature contrast, and location, thus solving the degeneracy between them. Most notably, our model is also sensitive to convective motions. Results indicate a reduced convective shift for M dwarfs when compared to solar-type stars (in agreement with theoretical extrapolations) and points to a small global convective redshift instead of blueshift. Conclusions. Using a novel approach based on simultaneous chromatic radial velocities and light curves, we can set strong constraints on stellar activity, including an elusive parameter such as the net convective motion effect.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs Period search in Hα, Na I D, and Ca II IRT lines
(EDP Sciences, 2019-02-27) Fuhrmeister, B.; Czesla, S.; Schmitt, J. H. M. M.; Johnson, E. N.; Schöfer, P.; Jeffers, S. V.; Caballero, J. A.; Zechmeister, M.; Reiners, A.; Ribas, I.; Amado, P. J.; Quirrenbach, A.; Bauer, F. F.; Béjar, V. J. S.; Cortés Contreras, M.; Díez Alonso, E.; Dreizler, S.; Galadí Enríquez, D.; Guenther, E. W.; Kaminski, A.; Kürster, M.; Lafarga, M.; Montes, D.; Deutsche Forschungsgemeinschaft (DFG); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We use spectra from CARMENES, the Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs, to search for periods in chromospheric indices in 16 M0–M2 dwarfs. We measure spectral indices in the Hα, the Ca II infrared triplet (IRT), and the Na I D lines to study which of these indices are best-suited to finding rotation periods in these stars. Moreover, we test a number of different period-search algorithms, namely the string length method, the phase dispersion minimisation, the generalized Lomb–Scargle periodogram, and the Gaussian process regression with quasi-periodic kernel. We find periods in four stars using Hα and in five stars using the Ca II IRT, two of which have not been found before. Our results show that both Hα and the Ca II IRT lines are well suited for period searches, with the Ca II IRT index performing slightly better than Hα. Unfortunately, the Na I D lines are strongly affected by telluric airglow, and we could not find any rotation period using this index. Further, different definitions of the line indices have no major impact on the results. Comparing the different search methods, the string length method and the phase dispersion minimisation perform worst, while Gaussian process models produce the smallest numbers of false positives and non-detections.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs The He I triplet at 10830 Å across the M dwarf sequence
(EDP Sciences, 2019-11-25) Fuhrmeister, B.; Czesla, S.; Hildebrandt, L.; Nagel, E.; Schmitt, H. M. M.; Hintz, D.; Johnson, E. N.; Sanz Forcada, J.; Schöfer, P.; Jeffers, S. V.; Caballero, J. A.; Zechmeister, M.; Reiners, A.; Ribas, I.; Amado, P. J.; Quirrenbach, A.; Bauer, F. F.; Béjar, V. J. S.; Cortés Contreras, M.; Díez Alonso, E.; Dreizler, S.; Galadí Enríquez, D.; Guenther, E. W.; Kaminski, A.; Kürster, M.; Lafarga, M.; Montes, D.; Deutsche Forschungsgemeinschaft (DFG); Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); Ribas, I. [0000-0002-6689-0312]; Montes, D. [0000-0002-7779-238X]; Lafarga, M. [0000-0002-8815-9416]; Amado, P. [0000-0001-8012-3788]; Nagel, E. [0000-0002-4019-3631]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548
The He I infrared (IR) triplet at 10 830 Å is an important activity indicator for the Sun and in solar-type stars, however, it has rarely been studied in relation to M dwarfs to date. In this study, we use the time-averaged spectra of 319 single stars with spectral types ranging from M0.0 V to M9.0 V obtained with the CARMENES high resolution optical and near-infrared spectrograph at Calar Alto to study the properties of the He I IR triplet lines. In quiescence, we find the triplet in absorption with a decrease of the measured pseudo equivalent width (pEW) towards later sub-types. For stars later than M5.0 V, the He I triplet becomes undetectable in our study. This dependence on effective temperature may be related to a change in chromospheric conditions along the M dwarf sequence. When an emission in the triplet is observed, we attribute it to flaring. The absence of emission during quiescence is consistent with line formation by photo-ionisation and recombination, while flare emission may be caused by collisions within dense material. The He I triplet tends to increase in depth according to increasing activity levels, ultimately becoming filled in; however, we do not find a correlation between the pEW(He IR) and X-ray properties. This behaviour may be attributed to the absence of very inactive stars (LX∕Lbol < −5.5) in our sample or to the complex behaviour with regard to increasing depth and filling in.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs Three temperate-to-warm super-Earths
(EDP Sciences, 2020-11-10) Stock, S.; Nagel, E.; Kemmer, J.; Passegger, V. M.; Reffert, S.; Quirrenbach, A.; Caballero, J. A.; Czesla, S.; Béjar, V. J. S.; Cardona Guillén, C.; Díez Alonso, E.; Herrero, E.; Lalitha, S.; Schlecker, M.; Tal Or, L.; Rodríguez, E.; Rodríguez López, C.; Ribas, I.; Reiners, A.; Amado, P. J.; Bauer, F. F.; Bluhm, P.; Cortés Contreras, M.; González Cuesta, L.; Dreizler, S.; Hatzes, A. P.; Henning, T.; Jeffers, S. V.; Kaminski, A.; Kürster, M.; Lafarga, M.; López González, M. J.; Montes, D.; Morales, J. C.; Pedraz, S.; Schöfer, P.; Schweitzer, A.; Trifonov, T.; Zapatero Osorio, M. R.; Zechmeister, M.; Agencia Estatal de Investigación (AEI); Generalitat de Catalunya; National Aeronautics and Space Administration (NASA); Tel-Aviv University (Israel); Stock, S. [0000-0002-1166-9338]; Nagel, E. [0000-0002-4019-3631]; Kemmer, J. [0000-0003-3929-1442]; Reffert, S. [0000-0002-0460-8289]; Caballero, J. A. [0000-0002-7349-1387]; Cardona, C. [0000-0002-2198-4200]; Schlecker, M. [0000-0001-8355-2107]; Tal Or, L. [0000-0003-3757-1440]; Rodríguez, E. [0000-0001-6827-9077]; Ribas, I. [0000-0002-6689-0312]; Amado, P. J. [0000-0002-8388-6040]; Cortés Contreras, M. [0000-0003-3734-9866]; González Cuesta, L. [0000-0002-1241-5508]; López González, M. J. [0000-0001-8104-5128]; Zapatero Osorio, M. R. [0000-0001-5664-2852]; Zechmeister, M. [0000-0002-6532-4378]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548
We announce the discovery of two planets orbiting the M dwarfs GJ 251 (0.360 ± 0.015M⊙) and HD 238090 (0.578 ± 0.021M⊙) based on CARMENES radial velocity (RV) data. In addition, we independently confirm with CARMENES data the existence of Lalande 21185 b, a planet that has recently been discovered with the SOPHIE spectrograph. All three planets belong to the class of warm or temperate super-Earths and share similar properties. The orbital periods are 14.24 d, 13.67 d, and 12.95 d and the minimum masses are 4.0 ± 0.4 M⊕, 6.9 ± 0.9 M⊕, and 2.7 ± 0.3 M⊕ for GJ 251 b, HD 238090 b, and Lalande 21185 b, respectively. Based on the orbital and stellar properties, we estimate equilibrium temperatures of 351.0 ± 1.4 K for GJ 251 b, 469.6 ± 2.6 K for HD 238090 b, and 370.1 ± 6.8 K for Lalande 21185 b. For the latter we resolve the daily aliases that were present in the SOPHIE data and that hindered an unambiguous determination of the orbital period. We find no significant signals in any of our spectral activity indicators at the planetary periods. The RV observations were accompanied by contemporaneous photometric observations. We derive stellar rotation periods of 122.1 ± 2.2 d and 96.7 ± 3.7 d for GJ 251 and HD 238090, respectively. The RV data of all three stars exhibit significant signals at the rotational period or its first harmonic. For GJ 251 and Lalande 21185, we also find long-period signals around 600 d, and 2900 d, respectively, which we tentatively attribute to long-term magnetic cycles. We apply a Bayesian approach to carefully model the Keplerian signals simultaneously with the stellar activity using Gaussian process regression models and extensively search for additional significant planetary signals hidden behind the stellar activity. Current planet formation theories suggest that the three systems represent a common architecture, consistent with formation following the core accretion paradigm.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs. The He I infrared triplet lines in PHOENIX models of M 2-3 V stars
(EDP Sciences, 2020-06-24) Hintz, D.; Fuhrmeister, B.; Czesla, S.; Schmitt, H. M. M.; Schweitzer, A.; Nagel, E.; Johnson, E. N.; Caballero, J. A.; Zechmeister, M.; Jeffers, S. V.; Reiners, A.; Ribas, I.; Amado, P. J.; Quirrenbach, A.; Anglada Escudé, G.; Bauer, F. F.; Béjar, V. J. S.; Cortés Contreras, M.; Dreizler, S.; Galadí Enríquez, D.; Guenther, E. W.; Hauschildt, P. H.; Kaminski, A.; Kürster, M.; Lafarga, M.; López del Fresno, M.; Montes, D.; Morales, J. C.; Deutsches Zentrum für Luft- und Raumfahrt (DLR); Deutsche Forschungsgemeinschaft (DFG); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); 0000-0002-5274-2589; 0000-0001-6470-2907; 0000-0002-6532-4378; 0000-0003-1212-5225; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The He » I infrared (IR) line at a vacuum wavelength of 10 833 Å is a diagnostic for the investigation of atmospheres of stars and planets orbiting them. For the first time, we study the behavior of the He » I IR line in a set of chromospheric models for M-dwarf stars, whose much denser chromospheres may favor collisions for the level population over photoionization and recombination, which are believed to be dominant in solar-type stars. For this purpose, we use published PHOENIX models for stars of spectral types M2 V and M3 V and also compute new series of models with different levels of activity following an ansatz developed for the case of the Sun. We perform a detailed analysis of the behavior of the He I IR line within these models. We evaluate the line in relation to other chromospheric lines and also the influence of the extreme ultraviolet (EUV) radiation field. The analysis of the He » I IR line strengths as a function of the respective EUV radiation field strengths suggests that the mechanism of photoionization and recombination is necessary to form the line for inactive models, while collisions start to play a role in our most active models. Moreover, the published model set, which is optimized in the ranges of the Na » I D2, Hα, and the bluest Ca » II IR triplet line, gives an adequate prediction of the He » I IR line for most stars of the stellar sample. Because especially the most inactive stars with weak He » I IR lines are fit worst by our models, it seems that our assumption of a 100% filling factor of a single inactive component no longer holds for these stars. © ESO 2020.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs. Variability of the He I line at 10 830 Å
(EDP Sciences, 2020-08-10) Fihrmeister, B.; Czesla, S.; Hildebrandt, L.; Nagel, E.; Schmitt, H. M. M.; Jeffers, S. V.; Caballero, J. A.; Hintz, D.; Johnson, E. N.; Schöfer, P.; Zechmeister, M.; Reiners, A.; Ribas, I.; Amado, P. J.; Quirrenbach, A.; Nortmann, L.; Bauer, F. F.; Béjar, V. J. S.; Cortés Contreras, M.; Dreizler, S.; Galadí Enríquez, D.; Hatzes, A. P.; Kaminski, A.; Kürster, M.; Lafarga, M.; Deutsche Forschungsgemeinschaft (DFG); Bauer, F. F. [0000-0003-1212-5225]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The He I infrared (IR) triplet at 10 830 Å is known as an activity indicator in solar-type stars and has become a primary diagnostic in exoplanetary transmission spectroscopy. He I IR lines are a tracer of the stellar extreme-ultraviolet irradiation from the transition region and corona. We study the variability of the He I triplet lines in a spectral time series of 319 M dwarf stars that was obtained with the CARMENES high-resolution optical and near-infrared spectrograph at Calar Alto. We detect He I IR line variability in 18% of our sample stars, all of which show Hα in emission. Therefore, we find detectable He I variability in 78% of the sub-sample of stars with Hα emission. Detectable variability is strongly concentrated in the latest spectral sub-types, where the He I lines during quiescence are typically weak. The fraction of stars with detectable He I variation remains lower than 10% for stars earlier than M3.0 V, while it exceeds 30% for the later spectral sub-types. Flares are accompanied by particularly pronounced line variations, including strongly broadened lines with red and blue asymmetries. However, we also find evidence for enhanced He I absorption, which is potentially associated with increased high-energy irradiation levels at flare onset. Generally, He I and Hα line variations tend to be correlated, with Hα being the most sensitive indicator in terms of pseudo-equivalent width variation. This makes the He I triplet a favourable target for planetary transmission spectroscopy. © 2020 ESO.
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs: Characterization of the nearby ultra-compact multiplanetary system YZ Ceti
(EDP Sciences, 2020-05-01) Stock, S.; Kemmer, J.; Reffert, S.; Trifonov, T.; Kaminski, A.; Dreizler, S.; Quirrenbach, A.; Caballero, J. A.; Reiners, A.; Anglada Escudé, G.; Ribas, I.; Amado, P. J.; Barrado, D.; Barnes, J. R.; Bauer, F. F.; Berdiñas, Z. M.; Béjar, V. J. S.; Coleman, G. A. L.; Cortés Contreras, M.; Díez Alonso, E.; Domínguez Fernández, A. J.; Espinoza, N.; Haswell, C. A.; Hatzes, A.; Henning, T.; Jenkins, J. S.; Jones, H. R. A.; Kossakowski, D.; Kürster, M.; Lafarga, M.; Lee, M. H.; López González, M. J.; Montes, D.; Morales, J. C.; Morales, N.; Pallé, E.; Pedraz, S.; Rodríguez, E.; Rodríguez López, C.; Zechmeister, M.; Jeffers, S. V.; Deutsche Forschungsgemeinschaft (DFG); Agencia Estatal de Investigación (AEI); Comisión Nacional de Investigación Científica y Tecnológica (CONICYT); Ministerio de Economía y Competitividad (MINECO); Junta de Andalucía; European Research Council (ERC); Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT); Science and Technology Facilities Council (STFC); Generalitat de Catalunya; 0000-0002-1166-9338; 0000-0003-3929-1442; 0000-0002-0460-8289; 0000-0002-0236-775X; 0000-0003-0203-8208; 0000-0002-7349-1387; 0000-0003-2490-4779; 0000-0002-6689-0312; 0000-0002-8388-6040; 0000-0003-1930-5683; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Acceso Abierto
The CARMENES search for exoplanets around M dwarfs: LP 714-47 b (TOI 442.01): populating the Neptune desert
(EDP Sciences, 2020-12-11) Dreizler, S.; Crossfield, J. M.; Kossakowski, D.; Plavchan, P.; Jeffers, S. V.; Kemmer, J.; Luque, R.; Espinoza, N.; Pallé, E.; Stassun, K.; Matthews, E.; Gorjian, V.; Kawauchi, K.; Kielkopf, J. F.; Hidalgo, D.; Kosiarek, M. R.; Kreidberg, L.; Huber, D.; Livingston, J.; Jehin, E.; Jensen, E. L. N.; Mann, A.; Madrigal Aguado, A.; Kane, S. R.; Mocnik, T.; Morales, J. C.; Klahr, H.; Murgas Alcaino, F.; Kürster, M.; Lafarga, M.; Nowak, G.; Louie, D.; Parviainen, H.; Passegger, V. M.; Matson, R. A.; Pozuelos, F. J.; Quirrenbach, A.; Muirhead, P. S.; Robertson, P.; Nandakumar, S.; Narita, N.; Rose, M. E.; Roy, A.; Oshagh, M.; Schlieder, J.; Shectman, S.; Pollacco, D.; Senavci, H. V.; Reefe, M.; Ribas, I.; Villaseñor, J. N.; Rodríguez López, C.; Weiss, L. M.; Wittrock, J.; Schweitzer, A.; Zohrabi, F.; Cale, B.; Tanner, A.; Lillo Box, J.; Teske, J.; Twicken, J. D.; Lalitha, S.; Reiners, A.; Wang, S. X.; Bitsch, B.; Zapatero Osorio, M. R.; Yilmaz, M.; Ricker, G.; Caballero, J. A.; Schlecker, M.; Seager, S.; Zechmeister, M.; Jenkins, J. M.; Aceituno, J.; Soubkiou, A.; Barkaoui, K.; Chaturvedi, P.; Hatzes, A. P.; Bauer, F. F.; Vanderspek, R.; Latham, D. W.; Benkhaldoun, Z.; Beichman, C.; Winn, J. N.; Butler, R. P.; Caldwell, D. A.; Amado, P. J.; Christianesen, J. L.; Barbieri, M.; Batalha, N. M.; Collins, K. A.; Benneke, B.; Combs, D.; Cortés Contreras, M.; Burt, J.; Daylan, T.; Chintada, A.; Chontos, A.; Evans, P.; Ciardi, D. R.; Cifuentes, C.; Flowers, E. E.; Fukui, A.; Collins, K. I.; Furlan, E.; Gaidos, E.; Crane, J. D.; Gillon, M.; Dragomir, D.; Esparza Borges, E.; Hellier, C.; Feng, F.; Howard, A. W.; Howell, Steve B.; Fulton, B.; Isaacson, I.; Geneser, C.; Giacalone, S.; Kaminski, A.; Gonzales, E.; Junta de Andalucia; National Aeronautics and Space Administration (NASA); European Research Council (ERC); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Generalitat de Catalunya; Science and Technology Facilities Council (STFC); Centre National de la Recherche Scientifique (CNRS); Japan Society for the Promotion of Science (KAKENHI); 0000-0001-6187-5941; 0000-0002-8864-1667; 0000-0003-3929-1442; 0000-0003-0987-1593; 0000-0002-7349-1387; 0000-0003-3742-1987; 0000-0002-8388-6040; 0000-0003-1715-5087; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We report the discovery of a Neptune-like planet (LP 714-47 b, P = 4.05204 d, m(b) = 30.8 +/- 1.5M(circle plus), R-b = 4.7 +/- 0.3 R-circle plus) located in the "hot Neptune desert". Confirmation of the TESS Object of Interest (TOI 442.01) was achieved with radial-velocity follow-up using CARMENES, ESPRESSO, HIRES, iSHELL, and PFS, as well as from photometric data using TESS, Spitzer, and ground-based photometry from MuSCAT2, TRAPPIST-South, MONET-South, the George Mason University telescope, the Las Cumbres Observatory Global Telescope network, the El Sauce telescope, the TuBTAK National Observatory, the University of Louisville Manner Telescope, and WASP-South. We also present high-spatial resolution adaptive optics imaging with the Gemini Near-Infrared Imager. The low uncertainties in the mass and radius determination place LP 714-47 b among physically well-characterised planets, allowing for a meaningful comparison with planet structure models. The host star LP 714-47 is a slowly rotating early M dwarf (T-eff = 3950 +/- 51 K) with a mass of 0.59 +/- 0.02M(circle dot) and a radius of 0.58 +/- 0.02R(circle dot). From long-term photometric monitoring and spectroscopic activity indicators, we determine a stellar rotation period of about 33 d. The stellar activity is also manifested as correlated noise in the radial-velocity data. In the power spectrum of the radial-velocity data, we detect a second signal with a period of 16 days in addition to the four-day signal of the planet. This could be shown to be a harmonic of the stellar rotation period or the signal of a second planet. It may be possible to tell the difference once more TESS data and radial-velocity data are obtained.
Acceso Abierto
Water vapor detection in the transmission spectra of HD 209458 b with the CARMENES NIR channel
(EDP Sciences, 2019-09-23) Sánchez López, A.; Alonso Floriano, F. J.; López Puertas, M.; Snellen, I. A. G.; Funke, B.; Nagel, E.; Bauer, F. F.; Amado, P. J.; Caballero, J. A.; Czesla, S.; Nortmann, L.; Pallé, E.; Salz, M.; Reiners, A.; Ribas, I.; Quirrenbach, A.; Anglada Escudé, G.; Béjar, V. J. S.; Casasayas Barris, N.; Galadí Enríquez, D.; Guenther, E. W.; Henning, T.; Kaminski, A.; Kürster, M.; Lampón, M.; Lara, L. M.; Montes, D.; Morales, J. C.; Stangret, M.; Tal Or, L.; Sanz Forcada, J.; Schmitt, J. H. M. M.; Zapatero Osorio, M. R.; Zechmeister, M.; Ministerio de Ciencia e Innovación (MICINN); Israel Science Foundation (ISF); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Sánchez López, A. [0000-0002-0516-7956]; Alonso Floriano, F. J. [0000-0003-1202-5734]; Snellen, I. [0000-0003-1624-3667]; Zapatero Osorio, M. R. [0000-0001-5664-2852]; 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
Aims. We aim at detecting water vapor in the atmosphere of the hot Jupiter HD 209458 b and perform a multi-band study in the near infrared with CARMENES. Methods. The water vapor absorption lines from the atmosphere of the planet are Doppler-shifted due to the large change in its radial velocity during transit. This shift is of the order of tens of km s−1, whilst the Earth’s telluric and the stellar lines can be considered quasi-static. We took advantage of this shift to remove the telluric and stellar lines using SYSREM, which performs a principal component analysis including proper error propagation. The residual spectra contain the signal from thousands of planetary molecular lines well below the noise level. We retrieve the information from those lines by cross-correlating the residual spectra with models of the atmospheric absorption of the planet. Results. We find a cross-correlation signal with a signal-to-noise ratio (S/N) of 6.4, revealing H2O in HD 209458 b. We obtain a net blueshift of the signal of –5.2 −1.3+2.6 km s−1 that, despite the large error bars, is a firm indication of day- to night-side winds at the terminator of this hot Jupiter. Additionally, we performed a multi-band study for the detection of H2O individually from the three near infrared bands covered by CARMENES. We detect H2O from its 0.96–1.06 μm band with a S/N of 5.8, and also find hints of a detection from the 1.06–1.26 μm band, with a low S/N of 2.8. No clear planetary signal is found from the 1.26–1.62 μm band. Conclusions. Our significant H2O signal at 0.96–1.06 μm in HD 209458 b represents the first detection of H2O from this band individually, the bluest one to date. The unfavorable observational conditions might be the reason for the inconclusive detection from the stronger 1.15 and 1.4 μm bands. H2O is detected from the 0.96–1.06 μm band in HD 209458 b, but hardly in HD 189733 b, which supports a stronger aerosol extinction in the latter, in line with previous studies. Future data gathered at more stable conditions and with larger S/N at both optical and near-infrared wavelengths could help to characterize the presence of aerosols in HD 209458 b and other planets.