Feeds

PLANET-SWAP shock: Stars grabbed dirtballs from other clusters

Galaxy was young then, explain boffins

Choosing a cloud hosting partner with confidence

Space boffins have suggested that billions of stars in our galaxy have captured roaming rogue planets as they tootle through the cosmos.

Artist's impression of a rogue planet tootling through the universe

Artist's impression of a rogue planet tootling through the universe.

Credit: Christine Pulliam (CfA)

The rogue planets, which can be ejected from their own star's system by interaction with a fellow planet during the early stages of a system's formation, float freely out in space. If they pass a different star later on, which is moving in the same direction and at the same speed, they can hitch a ride and end up trillions of miles away.

All this planet-swapping took place long ago in young star clusters. Boffins simulated these clusters and found if the number of rogue planets equaled the number of stars, there was a three to six per cent chance the stars would grab a planet over time.

The clusters then disperse, pulling once-neighbouring planets away from each other to end up hundreds or thousands of times farther from each other than the Earth is from the Sun.

Picking out which planets in the systems we can see are actually rogue planets isn't easy though. These worlds are likely to have an orbit that's tilted in comparison to planets native to the star they end up with, and might even orbit backwards.

But native planets can also end up in tilted orbits just because of the ordinary effects of gravity within a planetary system.

The best evidence to support the rogue planet capture theory was the discover in 2006 by the European Southern Observatory, which spotted two worlds orbiting each other without a star.

"The rogue double-planet system is the closest thing we have to a 'smoking gun' right now," said author Hagai Perets, from the Harvard-Smithsonian Centre for Astrophysics. "To get more proof, we'll have to build up statistics by studying a lot of planetary systems."

As for a rogue planet in our own solar system, astronomers haven't spotted one - yet.

"We can rule out large planets," Perets said. "But there's a non-zero chance that a small world might lurk on the fringes of our solar system."

Hagai Perets' study, co-authored by Thijs Kouwenhoven from Peking University in China, will be published in the next issue of the Astrophysical Journal. ®

Secure remote control for conventional and virtual desktops

More from The Register

next story
GRAV WAVE DRAMA: 'Big Bang echo' may have been grit on the scanner – boffins
Exit Planet Dust on faster-than-light expansion of universe
Mine Bitcoins with PENCIL and PAPER
Forget Sudoku, crunch SHA-256 algos
SpaceX Dragon cargo truck flies 3D printer to ISS: Clawdown in 3, 2...
Craft berths at space station with supplies, experiments, toys
'This BITE MARK is a SMOKING GUN': Boffins probe ancient assault
Tooth embedded in thigh bone may tell who pulled the trigger
DOLPHINS SMELL MAGNETS – did we hear that right, boffins?
Xavier's School for Gifted Magnetotaceans
Big dinosaur wowed females with its ENORMOUS HOOTER
That's right, Doris, I've got biggest snout in the prehistoric world
Japanese volcano eruption reportedly leaves 31 people presumed dead
Hopes fade of finding survivors on Mount Ontake
That glass of water you just drank? It was OLDER than the SUN
One MEELLION years older. Some of it anyway
Canberra drone team dances a samba in Outback Challenge
CSIRO's 'missing bushwalker' found and watered
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Storage capacity and performance optimization at Mizuno USA
Mizuno USA turn to Tegile storage technology to solve both their SAN and backup issues.
The next step in data security
With recent increased privacy concerns and computers becoming more powerful, the chance of hackers being able to crack smaller-sized RSA keys increases.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.
A strategic approach to identity relationship management
ForgeRock commissioned Forrester to evaluate companies’ IAM practices and requirements when it comes to customer-facing scenarios versus employee-facing ones.