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November 17, 2015

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Radiation is slamming the “most Earth-like planet,” scientists say

Nov. 17, 2015
Courtesy of the University of Warwick
and World Science staff

Vast amounts of radia­t­ion may be mak­ing life im­pos­si­ble on a plan­et that is con­sid­ered the most Earth-like known out­side our so­lar sys­tem, new re­search claims.

Sci­en­tists say radia­t­ion from a “su­per­flar­ing” red dwarf star, dubbed Kepler-438 may have stripped away the at­mos­phere of the plan­et, Kepler-438b. 

Artist's concep­tion of the red dwarf star Kep­ler-438 loom­ing next to its plan­et Kep­ler-438b. (Cre­dit: Mark A Gar­lick/U. of War­wick)


Reg­u­larly oc­cur­ring eve­ry few hun­dred days, the su­per­flares are about ten times more pow­er­ful than those ev­er recorded on the Sun, and equiv­a­lent in en­er­gy to tens of bil­lions of nu­clear bombs, ac­cord­ing to the re­search­ers, from the Uni­vers­ity of War­wick in the U.K. 

The dan­ger to the plan­etary at­mos­phere is­n’t the flares them­selves, he added, but an as­so­ci­at­ed phe­nom­e­non known as cor­o­nal mass ejec­tions, in which a star throws off gi­ant blobs of stel­lar ma­te­ri­al called plas­ma.

The re­sult­ing loss of at­mos­phere “could have se­ri­ous dam­ag­ing ef­fects on the hab­it­abil­ity of the plan­et,” said as­t­ro­phys­i­cist Da­vid Arm­strong at the uni­vers­ity, lead re­searcher of the re­search, pub­lished in the jour­nal Monthly No­tices of the Roy­al As­tro­nom­i­cal So­ci­e­ty.

“The pres­ence of an at­mos­phere is es­sen­tial for the de­vel­op­ment of life,” added Chlo­e Pugh of the uni­vers­ity, a col­la­bo­ra­tor in the proj­ect.

Kepler-438b, the plan­et with the high­est recorded “Earth Si­m­i­lar­ity In­dex,” is both si­m­i­lar in size and tem­per­a­ture to the Earth but is clos­er to its small star than the Earth is to the Sun.

“If the plan­et, Kepler-438b, has a mag­net­ic field like the Earth, it may be shielded from some of the ef­fects,” Arm­strong said. But “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.”

“Coro­nal mass ejec­tions are where a huge amount of plas­ma is hurled out­wards from the Sun,” said Pugh. “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.”


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Vast quantities of radiation may be making life impossible on a planet that is considered the most Earth-like known outside our solar system, new research claims. Scientists say radiation from a “superflaring” red dwarf star, dubbed Kepler-438 may have stripped away the atmosphere of the planet, Kepler-438b. Regularly occurring every few hundred days, the superflares are about ten times more powerful than those ever recorded on the Sun, and equivalent in energy to tens of billions of nuclear bombs, according to the researchers, from the University of Warwick in the U.K. The danger to the planetary atmosphere isn’t the flares themselves, he added, but an associated phenomenon known as coronal mass ejections, in which a star throws off giant blobs of stellar material called plasma. The resulting loss of atmosphere “could have serious damaging effects on the habitability of the planet,” said astrophysicist David Armstrong at the university, lead researcher of the research, published in the journal Monthly Notices of the Royal Astronomical Society. “The presence of an atmosphere is essential for the development of life,” added Chloe Pugh of the university, a collaborator in the project. Kepler-438b, the planet with the highest recorded “Earth Similarity Index,” is both similar in size and temperature to the Earth but is closer to its small star than the Earth is to the Sun. “If the planet, Kepler-438b, has a magnetic field like the Earth, it may be shielded from some of the effects,” Armstrong said. But “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.” “Coronal mass ejections are where a huge amount of plasma is hurled outwards from the Sun,” said Pugh. “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.”