%0 Journal Article
%A Montes Gutiérrez, David
%T Ground-based detection of an extended helium atmosphere in the Saturn-mass exoplanet WASP-69b
%D 2018
%@ 0036-8075
%U https://hdl.handle.net/20.500.14352/13138
%X Hot gas giant exoplanets can lose part of their atmosphere due to strong stellar irradiation, affecting their physical and chemical evolution. Studies of atmospheric escape from 2 exoplanets have mostly relied on space-based observations of the hydrogen Lyman-α line in the far ultraviolet which is strongly affected by interstellar absorption. Using ground-based high-resolution spectroscopy we detect excess absorption in the helium triplet at 1083 nm during the transit of the Saturn-mass exoplanet WASP-69b, at a signal-to-noise ratio of 18. We measure line blue shifts of several km s^(-1) and post transit absorption, which we interpret as the escape of part of the atmosphere trailing behind the planet in comet-like form.
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