Hottest known exoplanet slowly being 'eaten' by its parent star

Astronomers have reported that one of the hottest known planets outside our solar system is slowly being "eaten" by its parent star.

First described in 2008, the exoplanet-WASP-12b is a Jupiter-like world that orbits its host star so tightly a year lasts just 26 hours.

This closeness means that a combination of heat from the star and from a gravitational tug-of-war called tidal heating brings the surface temperature to more than 4,700 degrees Fahrenheit (2,600 degrees Celsius).

According to a report in National Geographic News, new data show that WASP-12b's atmosphere is also being puffed up by the star's heat to the point that some of its gases are escaping.

"But rather than being blown away by stellar winds, the lost atmosphere might be getting pulled toward the star to form a hot ring around the star," said study leader Shu-lin Li, an astronomer at Peking University in Beijing.

In fact, WASP-12b is losing mass so fast, it will likely disappear before its aging star has a chance to swallow the planet whole.

"The sun like host star, known as WASP-12, is now about two billion years old, which means it's nearing the end of its life," said Heather Knutson, an astronomer and exoplanet researcher at the University of California, Berkeley.

"Normally, dying sun like stars grow into red giants, and their outer atmospheres expand to engulf nearby planets," said Knutson.

WASP-12b has expanded to six times Jupiter's volume, even though the planet is only about 1.4 times Jupiter's mass.

It is predicted to become a red giant within about a hundred million years.

But "this star will not have WASP-12b to 'eat,' because the planet would have been totally disrupted long before then, within ten million years," said study co-author Douglas Lin of the University of California, Santa Cruz.

"Overall, WASP-12b presents scientists with a rare chance to study a planet that can survive, for any length of time, so close to a star," said Knutson.

"They're in such extreme environments. You can imagine scenarios in which there are other planets we didn't see that got that close and didn't make it," she added.