Planet 10 times the size of Jupiter discovered, when it shouldn’t even exist

This artist’s impression shows a close up of the planet b Centauri b, which orbits a binary system with mass at least six times that of the Sun. This is the most massive and hottest planet-hosting star system found to date. Courtesy / ESO

Astronomers have spotted a planet about 10 times the size of Jupiter orbiting a B-type star that is more than three times as hot as the sun.

The details of the discovered planet, named b Centauri b, were published in Nature this week. It is one of the most massive planets ever spotted and, based on what researchers know about planet formation, it technically shouldn’t exist.

The European Southern Observatory’s Very Large Telescope in Chile spotted the large mass in the constellation Centaurus, orbiting “b Centauri” — a pair of stars at least six times the mass of the sun, and gravitationally bound to one another.

The planet’s orbit is about 100 times wider than Jupiter’s orbit around our sun and about 560 times wider than Earth’s, and researchers say it’s the hottest and most massive planet-hosting system found to date.

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This image shows the most massive planet-hosting star pair to date, b Centauri, and its giant planet, b Centauri b.
This image shows the most massive planet-hosting star pair to date, b Centauri, and its giant planet, b Centauri b. Courtesy / ESO

Until this recent discovery, which is located about 325 light years from Earth, no planet has ever been found orbiting a star more than three times the sun’s mass. Until now, some astronomers believed planets could not exist around stars this massive and this hot.

Planets form from material coming together inside huge disks of swirling gas and dust surrounding newborn stars. Stars larger than that emit so much high-energy radiation that they were thought to torch the planetary formation process. This discovery shatters that view.

Researchers said the “results show that planets can reside in much more massive stellar systems than what would be expected from extrapolation of previous results.”

“Finding a planet around b Centauri was very exciting since it completely changes the picture about massive stars as planet hosts,” said Markus Janson, an astronomer at Stockholm University in Sweden and an author of the study.

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“B-type stars are generally considered as quite destructive and dangerous environments, so it was believed that it should be exceedingly difficult to form large planets around them,” Janson said.

The study says the planet’s survival is likely credited to its massive orbiting distance from the central pair of stars.

“The planet in b Centauri is an alien world in an environment that is completely different from what we experience here on Earth and in our Solar System,” said co-author Gayathri Viswanath, a PhD student at Stockholm University.

“It’s a harsh environment, dominated by extreme radiation, where everything is on a gigantic scale: the stars are bigger, the planet is bigger, the distances are bigger.”

It isn’t the first time the planet has been picked up by space imaging. Twenty years ago, researchers imaged it, but it wasn’t until current teams examined the archival data that it was able to be classified as a planet.

— with files from Reuters


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