07 April 2008

Astronomers have discovered a planetary system orbiting a distant star which has similarities to our own: they found two planets that were close matches for Jupiter and Saturn orbiting a star about half the size of our Sun.

Martin Dominik, from St Andrews University in the UK, said the finding suggested systems like our own could be much more common than we thought. The St Andrews researcher said this planetary system, and others like it, could host terrestrial planets like Earth. It was just a matter of time before such worlds were detected, he explained. "We found a system with two planets that take the roles of Jupiter and Saturn in our Solar System. These two planets have a similar mass ratio and similar orbital radius and a similar orbital period. It looks like this may have formed in a similar way to our Solar System. And if this is the case, it looks like [our] Solar System cannot be unique in the Universe. There should be other similar systems out there which could host terrestrial planets."

The newfound planetary system, which orbits the star OGLE-2006-BLG-109L, is more compact than our own and is about five thousand light-years away. Although nearly 300 extrasolar planets have been identified, astronomers have consistently failed to find planetary systems which resemble our own. Dr Dominik said only 10% of systems discovered so far are known to host more than one planet.

But he explained that all the techniques currently used to find exoplanets were strongly biased towards detecting gas giant planets orbiting at short distances from their parent stars. The OGLE planets were found using a technique called gravitational micro-lensing, in which light from the faraway planets is bent and magnified by the gravity of a foreground object, in this case a another star.

He said that the ultimate goal for exoplanet researchers was to find habitable Earth-like and Mars-like planets. This aim was achievable, he said, because technology was improving all the time. "I think it will happen quite soon," he said, adding: "Micro-lensing can already go below Earth mass and it has detected more massive planets in the habitable zone. So in the next few years, we will see something really exciting."

Dr Dominik said there was competition between teams of astronomers using micro-lensing and those who favoured the transit technique, which seeks to detect new planets when, from our point of view, they pass directly in front of the parent star they are orbiting. The planet blocks a tiny fraction of the star's light, causing the star to periodically dim.

But he added that there was little chance to detect Earth-like worlds in OGLE-2006-BLG-109L because the system was too distant for current techniques to resolve planets the size of our own.


James Higham said...


Only Jams would run a post on this. :)

jams o donnell said...

Well I am still like a little boy when it comes to wonder at space!

Crushed said...

A little too far away for it to be realistically visitable though.

I think, it will be a millenium or two before we get there!

jams o donnell said...

Sadly so Crushed.. unless Zeparim Cochcrane gest born and invents the warp drive of course!

CherryPie said...

Fascinating :-)

jams o donnell said...

Glad you like it cherrypie!

elasticwaistbandlady said...

And suddenly the people that want you to pay to name a star after someone is now opening up their business to include naming planetary systems for your loved one.

We can place The Elastic Planet close to the Not-Wife planet! But only if she orbits around me. I want to be the alpha planetary system.

jams o donnell said...

Haha EWBL that would make her a satellite of the Elastic planet. Would you really want her to moon you!