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Discovery Alert: Flaring Star, Toasted Planet - NASA Science:

A giant planet some 400 light-years away, HIP 67522 b, orbits its parent star so tightly that it appears to cause frequent flares from the star's surface, heating and inflating the planet's atmosphere.

On planet Earth, "space weather" caused by solar flares might disrupt radio communications, or even damage satellites. But Earth's atmosphere protects us from truly harmful effects, and we orbit the Sun at a respectable distance, out of reach of the flares themselves.

Not so for planet HIP 67522 b. A gas giant in a young star system – just 17 million years old – the planet takes only seven days to complete one orbit around its star. A "year," in other words, lasts barely as long as a week on Earth. That places the planet perilously close to the star. Worse, the star is of a type known to flare – especially in their youth.

[...] The star and the planet form a powerful but likely a destructive bond. In a manner not yet fully understood, the planet hooks into the star's magnetic field, triggering flares on the star's surface; the flares whiplash energy back to the planet. Combined with other high-energy radiation from the star, the flare-induced heating appears to have increased the already steep inflation of the planet's atmosphere, giving HIP 67522 b a diameter comparable to our own planet Jupiter despite having just 5% of Jupiter's mass.

See also:

• Close-in planet induces flares on its host star
• Bizarre Case of a Planet Destroying Itself By Triggering the Star

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