A newly formed alien world may force scientists to rethink some of their ideas about planet formation.
One exoplanets A new study says that 11 times the mass of Jupiter lies in b Centauri, a young binary star system about 325 light-years from Earth.
The planet, known as b Centauri b, is one of the heaviest planets ever found. And combined, the two stars in b Centauri are worth 6 to 10 times more our sun, making this system the most massive in which a planet has been discovered to date. b Centauri is also the hottest known planet-hosting star system, the researchers said.
Study lead author Markus Janson, an astronomer at Stockholm University in Sweden, said: “Finding a planet around b Centauri is exciting, as it completely changes the picture of stars. Major stars are planetary hosts. said in a statement.
A large and hot star system
The two Centauri b stars are about 15 million years old – stars young compared to our sun, which have been burning for more than 4.5 billion years.
The duo’s combined mass would seem to make them unlikely to be planetary hosts. After all, the largest known harbor on the planet double star system contain 2.7 solar masses, and the heaviest single stars confirmed to have worlds orbiting them are about three times more massive than our sun, the team members said. know.
The heat and power of the Centauri b system reinforce that bad parent’s assumption. The main star, b Centauri A, is a B-type star with an estimated temperature of about 32,000 degrees Fahrenheit (18,000 degrees Celsius), the researchers say. It is about three times hotter than our G-type sun and hotter than any other planetary host star.
b Centauri B is therefore emitting a lot of high-energy ultraviolet and X-ray radiation, which tends to scatter the planet-forming dust and gas.
“B-class stars are generally considered to be quite destructive and dangerous environments,” says Janson. “It is believed that it is very difficult to form large planets around them.”
Beat the odds
The newly found planet has overcome those difficulties.
Janson and his colleagues discovered b Centauri b using the High-Contrast Alien Planetary Research (SPHERE) instrument, installed on the European Southern Observatory (ESO). Very large telescope in the country of Chile.
SPHERE captured the image of b Centauri b directly, a feat this tool has achieved some other exoplanets. Analysis of the SPHERE observations allowed the researchers to characterize the planet, which has other unusual features beyond the massive size, mass and heat of its parent stars. (The team’s study also revealed that ESO’s 3.6-meter telescope in Chile managed to image the newly formed planet more than 20 years ago, although no one realized it at the time. .)
For example, b Centauri b is currently located about 550 astronomical units (AU) from the duo – about 14 times farther than Pluto’s average distance from the sun. (One AU is the average Earth-Sun distance: about 93 million miles, or 150 million kilometers.)
It’s one of the widest known planetary orbits, the study’s authors published online Wednesday (December 8) in the journal Nature. Nature magazine. This immense distance could explain the planet’s existence, keeping it in a relatively safe position from the radiation blast from the Centauri b system’s core.
The origin story of b Centauri b is currently unclear. It may have formed relatively close to a binary through “core accretion“- the most common planet-forming process, in which dust particles in protoplanetary disks combine to form rocks. gravitational interactions, the team members said.
It is also possible that b Centauri b was born near its current location, where core accretion is less likely, due to the lower density of matter there. Thus, a distant formation, if it does occur, might involve another method known as “gravitational instability”.
“This top-down model requires that the mass of the protoplanetary disk be so great that part of the disk collapses under its own gravity. When this happens, a small secondary object is created. out and began to orbit the star,” Kaitlin Kratter, of the University of Arizona’s Steward Observatory, wrote in an accompanying article “News and Perspectives” in the same issue of the journal Nature.
“Gravity-unstable mechanisms also tend to produce very large objects – in fact, they can’t become planets,” added Kratter, who was not part of the research team. “Compared to the stars it orbits, the planet is small, making gravitational instability less likely than core accretion. Maybe it’s just a planet similar to the Stars. Jupiter, flies away from its star system through interactions with the stars it orbits. . An extensive investigation of planets involving massive stars will help clarify the exact formation mechanism its. “
Mike Wall is the author of “Out there“(Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow them on Twitter @Spacedotcom or above Facebook.
https://www.space.com/exoplanet-b-centauri-b-hot-massive-star-system Record-breaking alien planet discovered orbiting duo of supermassive, giant stars (pictured)