Ground-based detection of an extended helium atmosphere in the Saturn-mass exoplanet WASP-69b

Lisa Nortmann, Enric Pallé, Michael Salz, Jorge Sanz-Forcada, Evangelos Nagel, F. Javier Alonso-Floriano, Stefan Czesla, Fei Yan, Guo Chen, Ignas A.G. Snellen, Mathias Zechmeister, Jürgen H.M.M. Schmitt, Manuel López-Puertas, Núria Casasayas-Barris, Florian F. Bauer, Pedro J. Amado, José A. Caballero, Stefan Dreizler, Thomas Henning, Manuel LampónDavid Montes, Karan Molaverdikhani, Andreas Quirrenbach, Ansgar Reiners, Ignasi Ribas, Alejandro Sánchez-López, P. Christian Schneider, María R. Zapatero Osorio

    Research output: Contribution to journalArticleResearch

    86 Citations (Scopus)


    © 2018 American Association for the Advancement of Science. All rights reserved. Hot gas giant exoplanets can lose part of their atmosphere due to strong stellar irradiation, and these losses can affect their physical and chemical evolution. Studies of atmospheric escape from exoplanets have mostly relied on space-based observations of the hydrogen Lyman-a line in the far ultraviolet region, which is strongly affected by interstellar absorption. Using ground-based high-resolution spectroscopy, we detected excess absorption in the helium triplet at 1083 nanometers during the transit of the Saturn-mass exoplanet WASP-69b, at a signal-to-noise ratio of 18. We measured line blueshifts of several kilometers per second and posttransit absorption, which we interpret as the escape of part of the atmosphere trailing behind the planet in comet-like form.
    Original languageEnglish
    Pages (from-to)1388-1391
    Publication statusPublished - 21 Dec 2018


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