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Kepler-438b planet loses atmosphere to aggressive parent star

Wednesday, 18 November 2015 10:40 PM [ Last Update: Thursday, 19 November 2015 12:10 AM ]

In this artistic rendering, the planet Kepler-438b is shown in front of its violent parent star as it is being regularly irradiated by huge flares, which renders the planet uninhabitable. (University of Warwick)

Located some 470 light years away from the Earth in the constellation Lyra, Kepler-438b has been dubbed the most Earth-like exoplanet since its discovery by NASA earlier this year. Orbiting within the habitable zone of its parent star—a red dwarf called Kepler-438 -- the exoplanet has so far been considered as the most likely candidate for life. A new study; however, revealed that the superflaring parent has stripped the offspring from its atmosphere and thus left it uninhabitable.

The Earth’s magnetic field shields it from the most aggressive radiation emitted from the Sun and its right distance from its parent keeps it safe from boiling – like Mercury and Venus. But it seems that Kepler-438b neither has a strong magnetic field nor it is in the right distance from the parent to stay safe from its violent and dangerous radiation.

“Unlike the Earth's relatively quiet sun, Kepler-438 emits strong flares every few hundred days, each one stronger than the most powerful recorded flare on the Sun. It is likely that these flares are associated with coronal mass ejections, which could have serious damaging effects on the habitability of the planet,” said David Armstrong of the University of Warwick's Astrophysics Group and the lead author of the study, adding that the superflares are almost 10 times more powerful than those ever recorded on the Sun and equivalent to the same energy as 100 billion megatons of TNT.

However, the coronal mass ejection (CME), which occurs when a star hurls huge amount of plasma outwards, has a much more devastating role in eliminating a planet’s atmosphere than the superflare itself.

“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,” Armstrong added.

When atmosphere diminishes, the planet will be subject to harsh Ultraviolet and X-ray radiation from superflares, along with charged particle radiation, all of which are harmful to life.

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