When it comes to the search for Earth-like planets, Kepler-438b was the closest to having it all. It is only about 12 percent bigger than Earth and orbits in the “habitable zone” of its star, which is where scientists say the temperatures would be suitable for liquid water to exist on its surface.
But now in a new study, it has shown that Kepler-438b may not be all that it seems. Researchers, led by the University of Warwick, have found its red dwarf star (Kepler-438) may have stripped away its atmosphere as a result of radiation emitted from the super-flaring Red Dwarf star
The superflares regularly occur every few hundred days, and are about 10 times more powerful than those ever recorded on the Sun.
Kepler-438’s superflares are equivalent to the energy of 100 billion megatons of TNT, according to researchers.
It is unlikely the superflares themselves would have any significant impact on Kepler-438b’s atmosphere; it is the phenomenon associated with powerful flares that holds the danger. The phenomenon known as coronal mass ejection (CME) holds the potential to strip away any atmosphere, making a planet uninhabitable.
Chloe Pugh, of the University of Warwick’s Center for Fusion, Space, and Astrophysics, and co-author to the study, said: “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.
Dr. David Armstrong of the University of Warwick’s Astrophysics Group, who led the research, explained in a statement:
“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.
“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.”
“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,” Pugh added.
Kepler-438b lies about 470 light-years from Earth, and as the name suggests, it was discovered with NASA’s Kepler space telescope. Researchers say there is a 70 percent chance of it being rocky, and is the most Earth-like planet known to date, according to Earth Similarity Index (ESI).