Parent Stars May Strip Away the Atmospheres of Unprotected Planets with Solar Eruptions

The interplay between our closest star, the sun, and our planet is crucial for making Earth livable. Now, researchers have taken a closer look at the interplay between planets and stars, and have found that stars may actually rip oxygen from potentially habitable planets, making them unlivable.

Part of what protects our planet is its magnetosphere, a natural magnetic bubble that deflects coronal mass ejections (CMEs) and other particles hurled form the sun. Yet other planets, such as Venus, don't have this magnetosphere; on Dec. 19, 2006, the sun ejected a small, slow-moving puff of solar material that, although not very powerful, ripped dramatic amounts of oxygen out of Venus' atmosphere and into space.

"What if Earth didn't have that protective magnetosphere?" said Glyn Collinson, first author of the new study, in a news release. "Is a magnetosphere a prerequisite for a planet to support life? The jury is still out on that, but we examine such questions by looking at planets without magnetospheres, like Venus."

The researchers studied data from the Venus Express, which arrived at Venus in 2006 and carried out an eight-year mission. They found that on Dec. 23, 2006, the planet leaked oxygen at one of the highest densities ever seen. At the same time the particles were escaping, the data revealed that something unusual was occurring in the constant solar wind passing by the planet.

The researchers eventually pieced together that a weak CME had hit the planet. Although it was weak, though, it drastically affected Venus.

"The sun coughed out a CME that was fairly unimpressive," said Collinson. "But the planet reacted as if it had been hit by something massive. It turns out like the difference between putting a lobster in boiling water, versus putting it in cold water and heating it up slowly. Either way it doesn't go well for the lobster."

Currently, the researchers plan to continue looking at the Venus Express data. However, it appears as if planets without a magnetosphere may just be harmed by parent stars that rip away their atmosphere.

The findings are published in the Journal of Geophysical Research.

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