Astronomers spot gigantic planet 10 times more massive than Jupiter

A team of astronomers has captured an image of the hottest and most massive planet-hosting star system found to date.

The giant planet, named b Centauri (AB)b or b Centauri b, is located approximately 325 light-years away in the Centaurus constellation. It was detected orbiting a young massive binary star called b Centauri.

Visible to the naked eye, b Centauri b 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. This large distance from the central pair of stars could be key to the planet's survival. However, the planet is not to be confused with beta Centauri, a bright binary star.

"Finding a planet around b Centauri was very exciting since it completely changes the picture about massive stars hosting planets," explained Markus Janson, an astronomer at Stockholm University, Sweden.

The only 15 million years old b Centauri binary star has at least six times the mass of the Sun. This property makes it by far the most massive stellar system around which astronomers have found a planet. Until now, previous studies had failed to detect any such object around a star more than three times as massive as the Sun.

Most massive stars are also very hot, and this system is no exception: its primary star is a so-called B-type star that is over three times hotter than the Sun. Due to its high temperature, it emits large amounts of UV and X-ray radiation.

The large mass and heat from this type of star strongly impact the surrounding gas, which should counteract planet formation. In particular, the hotter a star is, the more high-energy radiation it produces. This property causes the surrounding material to evaporate more efficiently.

The new discovery demonstrates that planets can, in fact, form in such extreme stellar environments.

"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 points out.

"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 new planet, described in the paper published in the journal Nature, was spotted using sophisticated Spectro-Polarimetric High-contrast Exoplanet REsearch instrument (SPHERE) mounted on the Very Large Telescope (VLT) at the European Southern Observatory (ESO) in Chile.

Further, the team looked into past data on b Centauri and discovered that the planet had actually been imaged more than 20 years ago by the ESO 3.6-metre telescope, although it was not recognised as a planet at the time.