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The XUV irradiation and likely atmospheric escape of the super-Earth π Men c
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King, George W., Wheatley, Peter J., Bourrier, Vincent and Ehrenreich, David (2019) The XUV irradiation and likely atmospheric escape of the super-Earth π Men c. Monthly Notices of the Royal Astronomical Society: Letters, 484 (1). L49-L53. doi:10.1093/mnrasl/slz003 ISSN 1745-3925.
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WRAP-XUV-irradiation-atmospheric-escape-super-Earth-King-2019.pdf - Accepted Version - Requires a PDF viewer. Download (699Kb) | Preview |
Official URL: http://dx.doi.org/10.1093/mnrasl/slz003
Abstract
π Men c was recently announced as the first confirmed exoplanet from the TESS mission. The planet has a radius of just 2 R⊕ and it transits a nearby Sun-like star of naked-eye brightness, making it the ideal target for atmospheric characterization of a super-Earth. Here we analyse archival ROSAT and Swift observations of π Men in order to determine the X-ray and extreme-ultraviolet irradiation of the planetary atmosphere and assess whether atmospheric escape is likely to be on-going. We find that π Men has a similar level of X-ray emission to the Sun, with L_X/L_bol = (4.84^{+0.92}_{-0.84})× 10^{-7}. However, due to its small orbital separation, the high-energy irradiation of the super-Earth is around 2000 times stronger than suffered by the Earth. We show that this is sufficient to drive atmospheric escape at a rate greater than that readily detected from the warm Neptune GJ 436b. Furthermore, we estimate π Men to be four times brighter at Ly α than GJ 436. Given the small atmospheric scale heights of super-Earths, together with their potentially cloudy atmospheres, and the consequent difficulty in measuring transmission spectra, we conclude that ultraviolet absorption by material escaping π Men c presents the best opportunity currently to determine the atmospheric composition of a super-Earth.
Item Type: | Journal Article | |||||||||
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Subjects: | Q Science > QB Astronomy | |||||||||
Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | |||||||||
Library of Congress Subject Headings (LCSH): | Extrasolar planets | |||||||||
Journal or Publication Title: | Monthly Notices of the Royal Astronomical Society: Letters | |||||||||
Publisher: | Oxford University Press | |||||||||
ISSN: | 1745-3925 | |||||||||
Official Date: | 21 March 2019 | |||||||||
Dates: |
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Volume: | 484 | |||||||||
Number: | 1 | |||||||||
Page Range: | L49-L53 | |||||||||
DOI: | 10.1093/mnrasl/slz003 | |||||||||
Status: | Peer Reviewed | |||||||||
Publication Status: | Published | |||||||||
Reuse Statement (publisher, data, author rights): | This is a pre-copyedited, author-produced version of an article accepted for publication in George W King, Peter J Wheatley, Vincent Bourrier, David Ehrenreich; The XUV irradiation and likely atmospheric escape of the super-Earth π Men c, Monthly Notices of the Royal Astronomical Society: Letters, Volume 484, Issue 1, 21 March 2019, Pages L49–L53, following peer review. The version of record https://doi.org/10.1093/mnrasl/slz003 is available online | |||||||||
Access rights to Published version: | Restricted or Subscription Access | |||||||||
Date of first compliant deposit: | 8 February 2019 | |||||||||
Date of first compliant Open Access: | 11 February 2019 | |||||||||
RIOXX Funder/Project Grant: |
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