Extreme Radiation Makes Life Unlikely On Earth’s Twin
Vast amounts of radiation may have left one of the most Earth-like planets discovered uninhabitable.
The radiation is the result of a superflaring Red Dwarf star, Kepler-438. The flares occur regularly every few hundred days and are ten times more powerful than those ever recorded on the Sun—and equivalent to the same energy as 100 billion megatons of TNT.
While superflares themselves are unlikely to have a significant impact on Kepler-438b’s atmosphere, a dangerous phenomenon associated with powerful flares, known as a coronal mass ejection (CME), has the potential to strip away any atmosphere and render the planet uninhabitable.
The planet Kepler-438b, to date the exoplanet with the highest recorded Earth Similarity Index, is both similar in size and temperature to the Earth but is in closer proximity to the Red Dwarf than the Earth is to the Sun.
Magnetic Field Required
“If the planet, Kepler-438b, has a magnetic field like the Earth, it may be shielded from some of the effects. However, if it does not, or the flares are strong enough, it could have lost its atmosphere, be irradiated by extra dangerous radiation and be a much harsher place for life to exist,”
says David Armstrong of the University of Warwick’s Astrophysics Group, who led the study published in the Monthly Notices of the Royal Astronomical Society.
Discussing the impact of the superflares and radiation on the atmosphere of Kepler-438b, Chloe Pugh of the University of Warwick’s Centre for Fusion, Space and Astrophysics says:
“The presence of an atmosphere is essential for the development of life. While flares themselves are unlikely to have a significant impact on an atmosphere as a whole, there is another more dangerous phenomenon associated with powerful flares, known as a coronal mass ejection.
Coronal mass ejections are where a huge amount of plasma is hurled outwards from the Sun, and there is no reason why they should not occur on other active stars as well. The likelihood of a coronal mass ejection occurring increases with the occurrence of powerful flares, and large coronal mass ejections have the potential to strip away any atmosphere that a close-in planet like Kepler-438b might have, rendering it uninhabitable.
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.”
Illustration: Mark A Garlick/University of Warwick