Examinando por Autor "Huang, C. X."

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A remnant planetary core in the hot-Neptune desert
(Springer Nature Research Journals, 2020-07-01) Armstrong, D. J.; López, T. A.; Adibekyan, V.; Booth, R. A.; Bryant, E. M.; Collins, K. A.; Deleuil, M.; Emsenhuber, A.; Huang, C. X.; King, G. W.; Lillo Box, J.; Lissauer, J. J.; Matthews, E.; Mousis, O.; Nielsen, L. D.; Osborn, Hugh P.; Otegi, J.; Santos, N. C.; Sousa, S. G.; Stassun, K. G.; Veras, D.; Ziegler, C.; Acton, J. S.; Almenara, J. M.; Anderson, D. R.; Barrado, D.; Barros, S. C. C.; Bayliss, D.; Belardi, C.; Bouchy, F.; Briceño, C.; Brogi, M.; Brown, D. J. A.; Burleigh, M. R.; Casewell, S. L.; Chausev, A.; Ciardi, D. R.; Collins, K. I.; Colón, K. D.; Cooke, B. F.; Crossfield, J. M.; Díaz, R. F.; Delgado Mena, E.; Gandhi, O. D. S.; Gill, Samuel; Gonzales, E. J.; Goad, M. R.; Günther, M. N.; Helled, R.; Hojjatpanah, S.; Howell, Steve B.; Jackman, J.; Jenkins, J. S.; Jenkins, J. M.; Jensen, E. L. N.; Kennedy, G. M.; Latham, D. W.; Law, N.; Osborn, M.; Pollacco, D.; Queloz, D.; Raynard, L.; Ricker, G. R.; Rowden, P.; Santerne, A.; Schlieder, J. E.; Seager, S.; Sha, L.; Tan, T. G.; Tilbrook, R. H.; Ting, E.; Udry, S.; Vanderspek, R.; Watson, C. A.; West, R. G.; Wilson, P. A.; Winn, J. N.; Wheatley, P.; Villaseñor, J. N.; Vines, J. I.; Zhan, Z.; National Aeronautics and Space Administration (NASA); Fundação para a Ciência e a Tecnologia (FCT); Agencia Estatal de Investigación (AEI); Science and Technology Facilities Council (STFC); Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT); Collins, K. A. [0000-0002-4317-142X]; Lillo Box, J. [0000-0003-3742-1987]; Matthews, E. [0000-0003-0593-1560]; Sousa, S. [0000-0002-3631-6440]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The interiors of giant planets remain poorly understood. Even for the planets in the Solar System, difficulties in observation lead to large uncertainties in the properties of planetary cores. Exoplanets that have undergone rare evolutionary processes provide a route to understanding planetary interiors. Planets found in and near the typically barren hot-Neptune 'desert'(1,2)(a region in mass-radius space that contains few planets) have proved to be particularly valuable in this regard. These planets include HD149026b(3), which is thought to have an unusually massive core, and recent discoveries such as LTT9779b(4)and NGTS-4b(5), on which photoevaporation has removed a substantial part of their outer atmospheres. Here we report observations of the planet TOI-849b, which has a radius smaller than Neptune's but an anomalously large mass of39.1-2.6+2.7Earth masses and a density of5.2-0.8+0.7grams per cubic centimetre, similar to Earth's. Interior-structure models suggest that any gaseous envelope of pure hydrogen and helium consists of no more than3.9-0.9+0.8 per cent of the total planetary mass. The planet could have been a gas giant before undergoing extreme mass loss via thermal self-disruption or giant planet collisions, or it could have avoided substantial gas accretion, perhaps through gap opening or late formation(6). Although photoevaporation rates cannot account for the mass loss required to reduce a Jupiter-like gas giant, they can remove a small (a few Earth masses) hydrogen and helium envelope on timescales of several billion years, implying that any remaining atmosphere on TOI-849b is likely to be enriched by water or other volatiles from the planetary interior. We conclude that TOI-849b is the remnant core of a giant planet.
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, I. A. G.; 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.