Astronomers Discover Massive Planet 10 Times Bigger Than Jupiter

b Centauri and its giant planet b Centauri b, taken by the SPHERE instrument on ESO's Very Large Telescope and using a coronagraph. It blocked the immensely bright light from the massive star system (top left) and allowed astronomers to detect the faint planet (arrow). ESO/Janson et al

A group of astronomers has discovered one of the biggest planets ever found orbiting a massive and extremely hot two-star system, despite previously believing that such an environment was too inhospitable for a planet to form in.

The planet was discovered by Markus Janson, a professor of astronomy at Stockholm University, and colleagues, according to research published Wednesday in the science journal Nature.

Janson and his colleagues found the planet using the very sophisticated Spectro-Polarimetric High-contrast Exoplanet REsearch instrument (SPHERE) on the European Southern Observatory’s Very Large Telescope in Chile.

Named b Centauri (AB)b or b Centauri b, the planet is an “alien world experiencing conditions completely different from what we face here on Earth and in our Solar System,” astronomers said in a news release.

“It is 10 times more massive than Jupiter, making it one of the most massive planets ever found. Moreover, it revolves around the binary star at a staggering 100 times greater distance than Jupiter does from the Sun, one of the widest orbits discovered yet, ”astronomers explained. “This large distance from the central pair of stars could be key to the planet’s survival.”

Janson said the discovery of the planet around the two-star system completely changes what astronomers previously believed about massive stars hosting planets, and shows that they can, in fact, form in such severe star systems.

The two-star system, also named b Centauri, is 15 million years old and has at least six times the mass of the Sun, making it by far the biggest stellar system around which astronomers have found a planet. Owing to its incredibly high temperatures, the star system, which sits 325 light-years away in the Centaurus constellation, emits large amounts of UV and X-ray radiation.

Prior to its discovery, scientists had been unable to detect any such object around a star more than three times as massive as the Sun.

Furthermore, the large mass and heat emitted by the star system strongly impact the surrounding gas, which should technically make it difficult for planets to form.

“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.

“We have always had a very solar system-centric view of what planetary systems are ’supposed' to look like,” MPIA scientist and co-author Matthias Samland said. “Over the last 10 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 instrument used to discover the planet, the SPHERE, was constructed and built by a consortium of several astronomical institutions, and astronomers have so far used it to capture several planets orbiting stars other than the Sun before.

Using the instrument, they were able to take the first image of a growing infant planet and a potentially moon-forming disk.

“It will be an intriguing task to try to figure out how it might have formed, which is a mystery at the moment,” Janson added of the newly-discovered planet.