Astronomers discover ‘diamond-rich super-Earth’
55 Cancri e has a surface of mostly graphite surrounding a thick layer of diamond, below which is a layer of silicon-based minerals and a molten iron core. Picture: Haven Giguere
IT sounds just like a recent script from an episode of Dr Who. A diamond planet twice the size of the Earth and moving so fast that a year there lasts less than 24 hours has just been found by astronomers.
• ‘55 Cancri e’ is twice the size of Earth
• At least a third of planet could be diamond
• First glimpse of ‘fundamentally different chemistry’
A research team from America and France revealed yesterday that the planet, made largely out of diamonds, has been found orbiting a Sun-like star 40 light years away and is visible to the naked eye.
Experts estimate that at least a third of the planet’s mass could consist of diamonds.
It is not the first time that a diamond planet has been spotted but astronomers have never before seen one orbiting this kind of star or been able to study it in such detail.
Scientists say the find means that it can no longer be assumed distant rocky planets have a similar composition to Earth
Dr Nikku Madhusudhan, lead researcher at Yale University, whose findings are due to be published in the Astrophysical Journal Letters, said: “This is our first glimpse of a rocky world with a fundamentally different chemistry from Earth. The surface of this planet is likely covered in graphite and diamond rather than water and granite.”
David Spergel, an astronomer at Princeton University, said it was relatively simple to discover a star’s basic structure and history if you have its mass and age.
“Planets are much more complex,” he said. “This ‘diamond-rich super-Earth’ is likely just one example of the rich sets of discoveries that await us as we begin to explore planets around nearby stars.”
The rocky planet, called 55 Cancri e because it orbits a star known as 55 Cancri in the constellation of Cancer, is also very hot.
Temperatures on its surface can reach a blazing 3,900F, or 1,648C.
Its radius is twice Earth’s but it is much more dense, with a mass eight times greater, making it a “super-Earth”.
The planet is one of five orbiting 55 Cancri which can be seen from Earth in the Cancer star formation without a telescope.
It circles the star at hyper speed – a year lasts just 18 hours – compared to Earth’s 365 days.
Researchers first observed the planet last year but could not tell what it was made from.
Since then, they have been able to measure its radius and use that information, along with estimations of its mass, to calculate its chemical composition by computing all possible combinations of elements and compounds which would yield the characteristics found.
Astronomers had previously thought that the planet contained a substantial amount of super-heated water, based on the assumption that its chemical make-up was similar to Earth’s.
The new research suggests the planet has no water, and appears to be composed primarily of carbon, in the form of diamond and graphite, as well as iron, silicon carbide and possibly silicates. The study estimates at least a third of the planet’s mass – the equivalent of about three Earth masses – could be diamond.
Last year Dr Madhusudhan led the first study to find a planet with a carbon-rich atmosphere.
Experts estimate that it would take anywhere from 100,000 to 1.1 million years to reach the diamond planet using current technology, which can reach just 24,000 mph.
Popular TV science fiction series Dr Who has featured a toxic planet called Midnight with a landscape of diamonds.
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Tuesday 21 May 2013
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