Ardaseva, A;
Rimmer, PB;
Waldmann, I;
Rocchetto, M;
Yurchenko, SN;
Helling, C;
Tennyson, J;
(2017)
Lightning chemistry on Earth-like exoplanets.
Monthly Notices of the Royal Astronomical Society
, 470
(1)
pp. 187-196.
10.1093/mnras/stx1012.
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Abstract
We present a model for lightning shock-induced chemistry that can be applied to atmospheres of arbitrary H/C/N/O chemistry, hence for extrasolar planets and brown dwarfs. The model couples hydrodynamics and the STAND2015 kinetic gas-phase chemistry. For an exoplanet analogue to the contemporary Earth, our model predicts NO and NO 2 yields in agreement with observation. We predict height-dependent mixing ratios during a storm soon after a lightning shock of NO ≈ 10 -3 at 40 km and NO 2 ≈ 10 -4 below 40 km, with O 3 reduced to trace quantities (≪10 -10 ). For an Earth-like exoplanet with a CO 2 /N 2 dominated atmosphere and with an extremely intense lightning storm over its entire surface, we predict significant changes in the amount of NO, NO 2 , O 3 , H 2 O, H 2 and predict a significant abundance of C 2 N. We find that, for the Early Earth, O 2 is formed in large quantities by lightning but is rapidly processed by the photochemistry, consistent with previous work on lightning. The chemical effect of persistent global lightning storms are predicted to be significant, primarily due to NO 2 , with the largest spectral features present at ∼3.4 and ∼6.2 μm. The features within the transmission spectrum are on the order of 1 ppm and therefore are not likely detectable with the James Webb Space Telescope. Depending on its spectral properties, C 2 N could be a key tracer for lightning on Earth-like exoplanets with a N 2 /CO 2 bulk atmosphere, unless destroyed by yet unknown chemical reactions.
| Type: | Article |
|---|---|
| Title: | Lightning chemistry on Earth-like exoplanets |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stx1012 |
| Publisher version: | http://doi.org/10.1093/mnras/stx1012 |
| Language: | English |
| Additional information: | © 2017 The Author. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Astrobiology, atmospheric effects, hydrodynamics, molecular processes, Earth |
| 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.ucl.ac.uk/id/eprint/1554570 |
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