1. Helium in the eroding atmosphere of an exoplanet
- Author
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David Ehrenreich, Hannah R. Wakeford, Nikolay Nikolov, Aurélien Wyttenbach, Jonathan Irwin, David Charbonneau, David R. Anderson, Yifan Zhou, David K. Sing, Jayesh M. Goyal, Coel Hellier, Laura Kreidberg, Antonija Oklopčić, Sarah D. Blumenthal, Vincent Bourrier, Katy L. Chubb, Michael H. Williamson, Jessica Spake, Thomas M. Evans, Stéphane Udry, Benjamin V. Rackham, Gregory W. Henry, Nikku Madhusudhan, Nikku, Madhusudhan [0000-0002-4869-000X], and Apollo - University of Cambridge Repository
- Subjects
Solar System ,010504 meteorology & atmospheric sciences ,Gas giant ,FOS: Physical sciences ,chemistry.chemical_element ,Astrophysics ,01 natural sciences ,Atmosphere ,Planet ,QB460 ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Helium ,0105 earth and related environmental sciences ,Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,Multidisciplinary ,Billion years ,Exoplanet ,Radiation pressure ,chemistry ,13. Climate action ,astro-ph.EP ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
Helium is the second-most abundant element in the Universe after hydrogen and is one of the main constituents of gas-giant planets in our Solar System. Early theoretical models predicted helium to be among the most readily detectable species in the atmospheres of exoplanets, especially in extended and escaping atmospheres. Searches for helium, however, have hitherto been unsuccessful. Here we report observations of helium on an exoplanet, at a confidence level of 4.5 standard deviations. We measured the near- infrared transmission spectrum of the warm gas giant WASP-107b and identified the narrow absorption feature of excited metastable helium at 10,833 angstroms. The amplitude of the feature, in transit depth, is 0.049 +/- 0.011 per cent in a bandpass of 98 angstroms, which is more than five times greater than what could be caused by nominal stellar chromospheric activity. This large absorption signal suggests that WASP-107b has an extended atmosphere that is eroding at a total rate of 10^10 to 3 x 10^11 grams per second (0.1-4 per cent of its total mass per billion years), and may have a comet-like tail of gas shaped by radiation pressure., Comment: Accepted in Nature
- Published
- 2018