Feeds

Mega-planet spotted orbiting fading star

Big and clever

Top 5 reasons to deploy VMware with Tegile

Astronomers have discovered the biggest transiting exoplanet yet. Orbiting a fading star in the constellation of Hercules, planet TrES-4 is a whopping 70 per cent bigger than Jupiter.

Computer generated impression of the giant planet orbiting its home star. Credit: Jeffrey Hall, Lowell Observatory

To put these numbers in context, Jupiter is a mere 16 per cent (or so) bigger than Saturn, but is almost four times the mass. Although volume scales as the cube of the radius increases, as a planet gets heavier its increased gravity tends to collapse it inwards, and so the stepwise increase in mass is even steeper that you would expect.

But the alien world has a twist in its tale: despite its enormous size, it is less massive than our solar system's biggest planet, making it roughly as dense as a cork.

The planet is so diffuse, that its gravity only has the most tenuous of grasps on its upper atmosphere: the team at the Lowell Observatory who made the discovery suggests the planet probably has a diaphanous tail of material spiralling towards its parent star.

"It is about 70 percent bigger than Jupiter, the Solar System’s largest planet, but less massive, making it a planet of extremely low density. Its mean density is only about 0.2 grams per cubic centimetre, or about the density of balsa wood," says Georgi Mandushev, the lead author of the paper detailing the discovery.

And it the planet's density, or lack thereof, that has the boffins baffled.

"TrES-4 appears to be something of a theoretical problem,” said Edward Dunham, Lowell Observatory Instrument Scientist. "It is larger relative to its mass than current models of superheated giant planets can presently explain. Problems are good, though, since we learn new things by solving them."

As with all transiting planets, TrES-4 betrayed its existence by causing an observable dip in its parent star's brightness as it passed between the star and our telescopes. The transit was confirmed by the Sleuth telescope, maintained by David Charbonneau (CfA) and Francis O'Donovan (Caltech), at Caltech's Palomar Observatory.

The stats: TrES-4 is about 1400 light years from us, and orbits its parent star in three and a half days, at a distance of about 4.5m miles. This distance is small enough in astronomical terms (it is just 12 times the distance from Earth to the moon) that the planet's surface is extremely hot, clocking in at around 1,600 Kelvin. ®

Beginner's guide to SSL certificates

More from The Register

next story
Renewable energy 'simply WON'T WORK': Top Google engineers
Windmills, solar, tidal - all a 'false hope', say Stanford PhDs
SEX BEAST SEALS may be egging each other on to ATTACK PENGUINS
Boffin: 'I think the behaviour is increasing in frequency'
The next big thing in medical science: POO TRANSPLANTS
Your brother's gonna die, kid, unless we can give him your, well ...
Post-pub nosh neckfiller: The MIGHTY Scotch egg
Off to the boozer? This delicacy might help mitigate the effects
I'M SO SORRY, sobs Rosetta Brit boffin in 'sexist' sexy shirt storm
'He is just being himself' says proud mum of larger-than-life physicist
NASA launches new climate model at SC14
75 days of supercomputing later ...
Britain's HUMAN DNA-strewing Moon mission rakes in £200k
3 days, and Kickstarter moves lander 37% nearer takeoff
prev story

Whitepapers

Why cloud backup?
Combining the latest advancements in disk-based backup with secure, integrated, cloud technologies offer organizations fast and assured recovery of their critical enterprise data.
Getting started with customer-focused identity management
Learn why identity is a fundamental requirement to digital growth, and how without it there is no way to identify and engage customers in a meaningful way.
5 critical considerations for enterprise cloud backup
Key considerations when evaluating cloud backup solutions to ensure adequate protection security and availability of enterprise data.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Simplify SSL certificate management across the enterprise
Simple steps to take control of SSL across the enterprise, and recommendations for a management platform for full visibility and single-point of control for these Certificates.