Even thought it is one of the potentially habitable exoplanets, researchers removed Kepler-438b from the list of habitable exoplanets because of the high-energy radiation at its surface generated by its host star.
Kepler-438b is a planet located outside our solar system that is only 12 percent larger than our planet and its position to its host star allows it to have just the right temperatures to be qualified as habitable.
But the exoplanet is different from Earth. Every few months, its host star, a still-active red dwarf ejects ‘superflares’ of radiation into the planet’s direction. Scientists said that these stellar flares are more powerful than the most powerful of our sun’s ejections to date.
Nevertheless, while the flares do not have a decisive impact on Kepler-438b’ habitability, if they come bundled with massive plasma explosions, also known as coronal mass ejections in our sun’s case, life may not stand a high chance on the said exoplanet, researchers explained.
Chloe Pugh, lead author of the study and PhD student at the University of Warwick in England, argued that major coronal mass ejections can leave a closely orbiting planet without an atmosphere, which may bring the probability for it to be habitable close to zero.
Although Kepler-438b is also closely orbiting (it orbits its host star every 35 days) is still located in the ‘habitable zone.’ This means that the proximity to its host star does not trigger temperatures so high on its surface that may discourage life.
Scientists explained that if Kepler-438b’s host star was the sun, the exoplanet wouldn’t have qualified as a habitable planet because our star is considerably hotter and brighter than the red dwarf Kepler-438b is orbiting.
Pugh also said that a planet stripped of its atmosphere can no longer render harsh ultraviolet and X-ray radiation coming from superflares harmless. This radiation along with charged particles are extremely ‘damaging to life.’
Nevertheless, despite severe radiation coming from the star, Kepler-438b could still preserve its atmosphere if it has a strong magnetic field just like our planet does. But if there is no such field, the superflares are strong enough to make it completely lose its atmosphere, researchers noted.
As a result, the planet may be a barren, highly irradiated world and one of the harshest environments for life to exist. The exoplanet was named after the telescope that first found it – the Kepler space telescope. According to calculations, the exoplanet is located 470 light-years away.
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