03 December 2010
Testing the atmosphere of an exoplanet
Astronomers have managed for the first time to measure the atmosphere surrounding a "super-Earth" extrasolar planet.
Planet, GJ 1214b, which is 40 light years away, is three times larger than Earth and about seven times heavier, and is the first planet of its kind known to have an atmosphere.
According to the BBC researchers have found that it appears to have either a dense atmosphere of water steam, or is wrapped in thick clouds like Venus.
More experiments measuring more colours of light will bear out which it is.
The method used could be used on many ground-based telescopes to yield atmospheric data on other exoplanets. It works by canceling out the disruptive effects of the Earth's atmosphere while that of far-flung worlds is measured from the ground.
"'Super-Earths' are really interesting, they're at the forefront of what's going on in exoplanet research," said Jacob Bean, the Harvard-Smithsonian University Center for Astrophysics scientist who led the research. "They're an interesting regime because they're defined as being the transition from terrestrial planets like Earth, Venus and Mars, up to the ice giants like Uranus and Neptune."
From what is known about GJ 1214b, three theories of its composition and atmosphere dominated. It could either be covered in a dense layer of steam, or it could be an icy, rocky world with a hydrogen or helium atmosphere, or perhaps a large rocky planet with a mixture of volcanic gases.
Drake Deming, of Nasa's Planetary Systems Laboratory said the work "opens the door to characterisng these kinds of super-Earth atmospheres".
"We've been seduced by the abundance of exoplanet results into thinking that these are routine measurements, but they're actually extraordinarily difficult," he told BBC News.
"This is certainly the most significant atmospheric exoplanet result in the last year - and a year is a long time in this field."
The next step is to carry out the same measurement using different colours of light, further into the infrared where the distinction can be made; .
I may be an utter ignoramus where physics is concerned but this is truly fascinating stuff. I daresay in a few years time such results will be routine