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arXiv · 1804.11124

The XUV environments of exoplanets from Jupiter-size to super-Earth

George W. King·Peter J. Wheatley·Michael Salz·Vincent Bourrier·Stefan Czesla·David Ehrenreich·James Kirk·Alain Lecavelier des Etangs·Tom Louden·Jürgen Schmitt·P. Christian Schneider
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Abstract

Planets that reside close-in to their host star are subject to intense high-energy irradiation. Extreme-ultraviolet (EUV) and X-ray radiation (together, XUV) is thought to drive mass loss from planets with volatile envelopes. We present $\textit{XMM-Newton}$ observations of six nearby stars hosting transiting planets in tight orbits (with orbital period, $P_\text{orb} < 10\,$d), wherein we characterise the XUV emission from the stars and subsequent irradiation levels at the planets. In order to reconstruct the unobservable EUV emission, we derive a new set of relations from Solar $\textit{TIMED/SEE}$ data that are applicable to the standard bands of the current generation of X-ray instruments. From our sample, WASP-80b and HD$\,$149026b experience the highest irradiation level, but HAT-P-11b is probably the best candidate for Ly$\,\alpha$ evaporation investigations because of the system's proximity to the Solar System. The four smallest planets have likely lost a greater percentage of their mass over their lives than their larger counterparts. We also detect the transit of WASP-80b in the near ultraviolet with the Optical Monitor on $\textit{XMM-Newton}$.

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George W. King, Peter J. Wheatley, Michael Salz, Vincent Bourrier, Stefan Czesla, David Ehrenreich, James Kirk, Alain Lecavelier des Etangs, Tom Louden, Jürgen Schmitt, P. Christian Schneider. 2018-04-30. The XUV environments of exoplanets from Jupiter-size to super-Earth. https://doi.org/10.1093/mnras%2Fsty1110

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