Spake, JJ;
Sing, DK;
Evans, TM;
Oklopcic, A;
Bourrier, V;
Kreidberg, L;
Rackham, BV;
... Madhusudhan, N; + view all
(2018)
Helium in the eroding atmosphere of an exoplanet.
Nature
, 557
pp. 68-70.
10.1038/s41586-018-0067-5.
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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 atmospheres1. Searches for helium, however, have hitherto been unsuccessful2. 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 giant3 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 1010 to 3 × 1011 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.
| Type: | Article |
|---|---|
| Title: | Helium in the eroding atmosphere of an exoplanet |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1038/s41586-018-0067-5 |
| Publisher version: | https://doi.org/10.1038/s41586-018-0067-5 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Science & Technology, Multidisciplinary Sciences, Science & Technology - Other Topics, NEPTUNE-MASS EXOPLANET, TRANSMISSION SPECTROSCOPY, M-DWARFS, STARS, ANGSTROM, EVOLUTION, EXOSPHERE, SPECTRUM, ROTATION, PLANETS |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10092129 |
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