From Warwick U:
The most Earth-like planet could have been made uninhabitable by vast quantities of radiation, new research led by the University of Warwick has found.
The atmosphere of the planet, Kepler-438b, is thought to have been stripped away as a result of radiation emitted from a superflaring Red Dwarf star, Kepler-438.
Regularly occurring every few hundred days, the superflares are approximately ten times more powerful than those ever recorded on the Sun and equivalent to the same energy as 100 billion megatons of TNT.More.
The find raises a question about how we determine whether a planet is Earth-like.
Most Earth-like planet uninhabitable due to radiation, new research suggests
Farewell to hope of life on Kepler-438b,
“With little atmosphere, the planet would also be subject to harsh UV and X-ray radiation from the superflares, along with charged particle radiation, all of which are damaging to life,” explained study co-author Chloe Pugh of the university’s Centre for Fusion, Space and Astrophysics.
The search for extraterrestrial life is not yet over, though. To date, the Kepler mission has identified 1,030 candidate planets, many of which have not yet been studied in great detail.
See also: Don’t let Mars fool you. Those exoplanets teem with life!
Here’s the abstract:
We embark on a detailed study of the lightcurves of Kepler ‘s most Earth-like exoplanet host stars using the full length of Kepler data.We derive rotation periods, photometric activity indices, aring energies, mass loss rates, gyrochronological ages, X-ray lumi nosities and consider implications for the planetary magnetospheres and habitability. Furthermore, we present the detection of superares in the lightcurve of Kepler-438,the exoplanet with the highest Earth Similarity Index to date. Kepler-438b orbits at a distance of 0.166AU to its host star, and hence may be susceptible to atmospheric stripping. Our sample is taken from the Habitable Exoplanet Catalogue, and consists of the stars Kepler-22, Kepler-61, Kepler-62, Kepler-174, Kepler-186, Kepler-283, Kepler-296,Kepler-298, Kepler-438, Kepler-440, Kepler-442, Kepler-443 and KOI-4427, between them hosting 15 of the most habitable transiting planets known to date from Kepler. – D. J. Armstrong, C. E. Pugh, A.-M. Broomhall, D. J. A. Brown, M. N. Lund, H. P. Osborn, D. L. Pollacco, The Host Stars of Keplers Habitable Exoplanets: Superflares, Rotation and Activity
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