Examinando por Autor "Strangret, M."

Mostrando 1 - 5 de 5

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
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
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
The atmosphere of HD 209458b seen with ESPRESSO No detectable planetary absorptions at high resolution
(EDP Sciences, 2021-03-02) Casasayas Barris, N.; Pallé, E.; Strangret, M.; Bourrier, V.; Tabernero, H. M.; Yan, F.; Borsa, F.; Allart, R.; Zapatero Osorio, M. R.; Lovis, C.; Sousa, S. G.; Chen, G.; Oshagh, M.; Santos, N. C.; Pepe, F.; Rebolo, R.; Molaro, P.; Cristiani, S.; Adibekyan, V.; Alibert, Y.; Allende Prieto, C.; Bouchy, F.; Demangeon, O. D. S.; Di Marcoantonio, P.; D´Odorico, V.; Ehrenreich, D.; Figueira, P.; Génova Santos, R.; Lavie, B.; Lillo Box, J.; Lo Curto, G.; Martins, C. J. A. P.; Mehner, A.; Micela, G.; Nunes, N. J.; Poretti, E.; Sozzetti, A.; Suárez Mascareño, A.; Udry, S.; González Hernández, Carmen; National Natural Science Foundation of China (NSFC); Deutsche Forschungsgemeinschaft (DFG); European Research Council (ERC); Fundacao para a Ciencia e a Tecnologia (FCT); Istituto Nazionale di Astrofisica (INAF); Agencia Estatal de Investigación (AEI); Swiss National Science Foundation (SNSF); Yan, F. [0000-0001-9585-9034]; Sozzetti, A. [0000-0002-7504-365X]; Nunes, N. [0000-0002-3837-6914]; Santos, N. [0000-0003-4422-2919]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We observed two transits of the iconic gas giant HD 209458b between 380 and 780 nm, using the high-resolution ESPRESSO spectrograph. The derived planetary transmission spectrum exhibits features at all wavelengths where the parent star shows strong absorption lines, for example, Na I, Mg I, Fe I, Fe II, Ca I, V I, Hα, and K I. We interpreted these features as the signature of the deformation of the stellar line profiles due to the Rossiter-McLaughlin effect, combined with the centre-to-limb effects on the stellar surface, which is in agreement with similar reports recently presented in the literature. We also searched for species that might be present in the planetary atmosphere but not in the stellar spectra, such as TiO and VO, and obtained a negative result. Thus, we find no evidence of any planetary absorption, including previously reported Na I, in the atmosphere of HD 209458b. The high signal-to-noise ratio in the transmission spectrum (~1700 at 590 nm) allows us to compare the modelled deformation of the stellar lines in assuming different one-dimensional stellar atmospheric models. We conclude that the differences among various models and observations remain within the precision limits of the data. However, the transmission light curves are better explained when the centre-to-limb variation is not included in the computation and only the Rossiter-McLaughlin deformation is considered. This demonstrates that ESPRESSO is currently the best facility for spatially resolving the stellar surface spectrum in the optical range using transit observations and carrying out empirical validations of stellar models.
Acceso Abierto
The widest broadband transmission spectrum (0.38–1.71 μm) of HD 189733b from ground-based chromatic Rossiter–McLaughlin observations
(EDP Sciences, 2020-11-03) Oshagh, M.; Bauer, F. F.; Lafarga, M.; Molaverdikhani, K.; Amado, P. J.; Nortmann, L.; Reiners, A.; Guzmán Mesa, A.; Pallé, E.; Nagel, E.; Caballero, J. A.; Casasayas Barris, N.; Claret, A.; Czesla, S.; Galadí Enríquez, D.; Henning, T.; Khalafinejad, S.; López Puertas, M.; Montes, D.; Quirrenbach, A.; Ribas, I.; Strangret, M.; Yan, F.; Zapatero Osorio, M. R.; Zechmeister, M.; Deutsche Forschungsgemeinschaft (DFG); European Regional Development Fund (ERDF); Agencia Estatal de Investigación (AEI); Oshagh, M. [0000-0002-0715-8789]; Guzman Mesa, A. [0000-0001-5762-0276]; 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
Multiband photometric transit observations (spectro-photometric) have been used mostly so far to retrieve broadband transmission spectra of transiting exoplanets in order to study their atmospheres. An alternative method was proposed, and has only been used once, to recover broadband transmission spectra using chromatic Rossiter–McLaughlin observations. We use the chromatic Rossiter–McLaughlin technique on archival and new observational data obtained with the HARPS and CARMENES instruments to retrieve transmission spectra of HD 189733b. The combined results cover the widest retrieved broadband transmission spectrum of an exoplanet obtained from ground-based observation. Our retrieved spectrum in the visible wavelength range shows the signature of a hazy atmosphere, and also includes an indication for the presence of sodium and potassium. These findings all agree with previous studies. The combined visible and near-infrared transmission spectrum exhibits a strong steep slope that may have several origins, such as a super-Rayleigh slope in the atmosphere of HD 189733b, an unknown systematic instrumental offset between the visible and near-infrared, or a strong stellar activity contamination. The host star is indeed known to be very active and might easily generate spurious features in the retrieved transmission spectra. Using our CARMENES observations, we assessed this scenario and place an informative constraint on some properties of the active regions of HD 189733. We demonstrate that the presence of starspots on HD 189733 can easily explain our observed strong slope in the broadband transmission spectrum.