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A planet has been found orbiting in a double-star system that is so hot and massive that some astronomers didn’t think a planet could exist around it.
The giant exoplanet, or planet located outside of our solar system, was discovered orbiting b Centauri, a stellar pair located 325 light-years from Earth in the Centaurus constellation. This is the hottest and most massive planet-hosting star system found so far.
Astronomers were able to capture an image of the planet using the European Southern Observatory’s Very Large Telescope in Chile. The binary star system is actually visible to us with the naked eye. The giant planet, which is 10 times as massive as Jupiter, orbits the pair of stars at 100 times the distance between Jupiter and the sun. It’s one of the most massive planets ever found.
A study detailing the image and findings published Wednesday in the journal Nature.
“Finding a planet around b Centauri was very exciting since it completely changes the picture about massive stars as planet hosts,” said lead study author Markus Janson, a professor of astronomy at Stockholm University, Sweden, in a statement.
The giant b Centauri binary star, which is astronomically young at 15 million years old – our sun is 4.6 billion years old – has at least six times the mass of our sun. Until this discovery, no planets have been found around stars with more than three times the mass of our star.
The stellar pair is also more than three times as hot as our sun, so it unleashes a tremendous amount of ultraviolet and X-ray radiation.
Unexpected planet with a wide orbit
All of these factors were expected to have a detrimental effect on the gas within the system, which would likely prevent planets from forming because highly energetic radiation causes material to evaporate more quickly.
“B-type stars are generally considered quite destructive and dangerous environments, so it was believed that it should be exceedingly difficult to form large planets around them,” Janson said.
Instead, the planet, dubbed b Centauri b, remains at such a large distance from its stars that this incredibly wide orbit probably allows the planet to survive.
“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 study coauthor Gayathri Viswanath, a doctoral student at Stockholm University, in a statement. “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.”
Rethinking planet formation
It’s just one of many discoveries rewriting what scientists understand about planet formation, especially under extreme circumstances.
“We have always had a very solar system centric view of what planetary systems are ‘supposed’ to look like,” said study coauthor Matthias Samland, a post-doctoral researcher at the Max Planck Institute for Astronomy, in a statement. “Over the last ten years, the discovery of many planetary systems in surprising and novel configurations has made us widen our historically narrow view. This discovery adds another exciting chapter to this story, this time for massive stars.”
The European Southern Observatory’s Extremely Large Telescope will come online later this decade, and its observational capabilities will allow scientists to begin understanding how this planet formed.
“It will be an intriguing task to try to figure out how it might have formed, which is a mystery at the moment,” Janson said.