Spectrally resolved helium absorption from the extended atmosphere of a warm Neptune-mass exoplanet.

Autor: Allart R; Observatoire Astronomique de l'Université de Genève, Université de Genève, Chemin des Maillettes 51, 1290 Versoix, Switzerland. romain.allart@unige.ch., Bourrier V; Observatoire Astronomique de l'Université de Genève, Université de Genève, Chemin des Maillettes 51, 1290 Versoix, Switzerland., Lovis C; Observatoire Astronomique de l'Université de Genève, Université de Genève, Chemin des Maillettes 51, 1290 Versoix, Switzerland., Ehrenreich D; Observatoire Astronomique de l'Université de Genève, Université de Genève, Chemin des Maillettes 51, 1290 Versoix, Switzerland., Spake JJ; Astrophysics Group, School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, UK., Wyttenbach A; Observatoire Astronomique de l'Université de Genève, Université de Genève, Chemin des Maillettes 51, 1290 Versoix, Switzerland.; Leiden Observatory, Leiden University, Postbus 9513, 2300 RA Leiden, Netherlands., Pino L; Observatoire Astronomique de l'Université de Genève, Université de Genève, Chemin des Maillettes 51, 1290 Versoix, Switzerland.; Dipartimento di Fisica e Astronomia 'Galileo Galilei,' Univ. di Padova, Vicolo dell'Osservatorio 3, Padova I-35122, Italy.; Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands., Pepe F; Observatoire Astronomique de l'Université de Genève, Université de Genève, Chemin des Maillettes 51, 1290 Versoix, Switzerland., Sing DK; Astrophysics Group, School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, UK.; Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD, USA., Lecavelier des Etangs A; Institut d'Astrophysique de Paris, CNRS, UMR 7095, Sorbonne Université, 98 bis boulevard Arago, Paris F-75014, France.
Jazyk: angličtina
Zdroj: Science (New York, N.Y.) [Science] 2018 Dec 21; Vol. 362 (6421), pp. 1384-1387. Date of Electronic Publication: 2018 Dec 06.
DOI: 10.1126/science.aat5879
Abstrakt: Stellar heating causes atmospheres of close-in exoplanets to expand and escape. These extended atmospheres are difficult to observe because their main spectral signature-neutral hydrogen at ultraviolet wavelengths-is strongly absorbed by interstellar medium. We report the detection of the near-infrared triplet of neutral helium in the transiting warm Neptune-mass exoplanet HAT-P-11b by using ground-based, high-resolution observations. The helium feature is repeatable over two independent transits, with an average absorption depth of 1.08 ± 0.05%. Interpreting absorption spectra with three-dimensional simulations of the planet's upper atmosphere suggests that it extends beyond 5 planetary radii, with a large-scale height and a helium mass loss rate of ≲3 × 10 5 grams per second. A net blue-shift of the absorption might be explained by high-altitude winds flowing at 3 kilometers per second from day to night-side.
(Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)
Databáze: MEDLINE
Externí odkaz: