Discovery of a diamond-studded planet
Wasp 12b is superheated by its parent star A US-British team of astronomers has
discovered the first planet with ultra-high concentrations of carbon.
An Indian scientist on December 10, 2010 announced the discovery of a carbon-rich
planet, named WASP-12b, orbiting a distant star about 1200 light years away from
the earth. This find is the first of a new class of exoplanetss and throws open
the possible existence of diamond-studded stars. Nikku Madhusudhan, a Benares
Hindu University alumini, and his colleagues at the Massachusetts Institute of
Technology recently measured the first-ever planetary atmosphere that is substantially enriched in carbon.
"The researchers found that the carbon-to-oxygen ratio of WASP-12b, an exoplanet
about 1.4 times the mass of Jupiter and located about 1,200 light years away, is
greater than one," Madhusudhan, who is now a postdoctoral researcher at
Princeton University, reported in a publication on December 10, 2010.
This carbon-rich atmosphere backs the possibility that exoplanets could be made
up of pure carbon rocks like diamond or graphite rather than the silica-based rock found in Earth.
WASP-12b is a very hot exoplanet, largely made of gas and has no surface to host
life. The work has been described as an astonishing astronomical tour de force.
They have detected the thermal radiation (heat) from a planet 1,200 light years
away using Nasa's Spitzer Space Telescope. From this information they have calculated the composition of its atmosphere,
according to Dr Marek Kukula of the Royal Greenwich Observatory in London.
Out of this world. "It is absolutely astonishing that these scientists are able to start to tease
out the details of what planets around other stars are made of," he said.
"The planet is thousands of times fainter than the star it orbits. So the
scientists have to perform an amazing feat of precision measurement to extract
anything at all. The fact that they are able to tell us something about the
composition of this particular planet is quite literally out of this world."
Many planets in our galaxy could have ultra-rich concentrations of carbon To
date astronomers have discovered more than 500 planets around other stars. These
distant worlds are known as exoplanets. It is only recently that instruments and analysis methods have become powerful
enough to discern their composition.
This new planet, Wasp 12b, is the first to have more carbon than oxygen. It is a
so-called gas giant, like Jupiter, and is mostly made from hydrogen gas.
But the planet's core could be composed of some form of diamond, graphite and
other carbon compounds, possibly in liquid form.
Tar pools planets
This discovery suggests there may well be many Earth-sized planets in our galaxy
that are ultra-rich in carbon. But these worlds would be unlike our planet: "Theoretical studies suggest that
they could be dominated by diamond and graphite rocks," according to Dr
Madhusudhan. "That would mean that in the mountains, a large fraction of the rock mass could
instead be made of diamonds and lots of land masses rich in diamonds, much more
than we see on Earth." These planets would be lacking in water So, if temperatures were sufficiently
high, liquid on their surface would consist of carbon-rich compounds, such as tar, he says.
So how common are these diamond planets? The short answer is that astronomers
simply don't know. But the fact that they've discovered one means that they'll
now start to try and find an answer. Dr Madhusudhan believes that they could be common.
"It's my strong belief that a fair fraction of the exoplanets we have discovered
could be carbon-rich and it's a very interesting thought that on such rocky
planets, sand could be a rare commodity and diamonds would be plentiful. The
more important question is how such planets could form."
An immediate question that is raised is why Wasp 12b is so much higher in carbon than the planets we know about.
The prevalent theory is that plenty of water ice was available when the planets
in our Solar System formed. That could not have been the case for Wasp 12b.