Astronomers Observe Exoplanet Temperatures Swinging Wildly

Posted May 4th, 2015 at 11:06 pm (UTC-4)
1 comment

Artist rendering of super-Earth exoplanet 55 Cancri e in close orbit with its sun. (NASA)

Artist rendering of super-Earth exoplanet 55 Cancri e in close orbit with its sun. (NASA)

For the first time ever, scientists in the United Kingdom detected temperature fluctuations on a super-Earth exoplanet – 55 Cancri e, the so-called “diamond planet.”

Using NASA’s Spitzer Space Telescope to study the rocky exoplanet’s thermal radiation over a two-year period, researchers led by the University of Cambridge found that the temperature on the side of the planet facing its nearby sun rapidly shifted between 1,000-2,700 degrees Celsius.

55 Cancri E is tidally locked, which means that it doesn’t rotate on its axis like Earth. So it has a permanent ‘day’ side that always faces its sun, and a permanent ‘night’ side – always away from its sun.

“This is the first time we’ve seen such drastic changes in light emitted from an exoplanet, which is particularly remarkable for a super-Earth,” said Nikku Madhusudhan of the University of Cambridge’s Institute of Astronomy in a press release.

Madhusudhan, who is also the co-author of a study published in the Monthly Notices of the Royal Astronomical Society, said “no signature of thermal emissions or surface activity has ever been detected for any other super-Earth to date.”

Past observations reveal that 55 Cancri e is a rocky exoplanet that is about twice the size of Earth and has eight times its mass. It orbits its parent star from such a close distance that one year there is only 18 hours long.

Artist impression showing surface of the rocky exoplanet 55 Cancri e with its sun in the background (Ron Miller/NASAblueshift)

Artist impression showing surface of the rocky exoplanet 55 Cancri e with its sun in the background (Ron Miller/NASAblueshift)

Along with five other exoplanets, 55 Cancri E orbits 55 Cancri, a Sun-like star located about 40 light years away in the Cancer constellation.

Back in 2012, Madhusudhan, then a researcher at Yale University, was lead author of a study that found that 55 Cancri e’s chemistry was much different from Earth. He and his colleagues found that the exoplanet’s surface was probably covered in graphite and diamond rather than water and granite like Earth.

It is now thought that the results of the new study may throw doubt on those earlier observations and that further study of the planet’s possible chemical composition is needed.

“When we first identified this planet, the measurements supported a carbon-rich model,” said Madhusudhan. “But now we’re finding that those measurements are changing in time. The planet could still be carbon rich, but now we’re not so sure. Earlier studies of this planet have even suggested that it could be a water world.”

Analysis of data is at an early stage, but the researchers think that enormous clouds of gas and dust that occasionally cover the exoplanet’s surface may be a contributing factor to the wide fluctuation of temperatures.

The researchers believe that these clouds of gas and dust, which could be partially molten, could be caused by a remarkably high amount of volcanic activity on 55 Cancri e.

“While we can’t be entirely sure, we think a likely explanation for this variability is large-scale surface activity – possibly volcanism … spewing out massive volumes of gas and dust, which sometimes blanket the thermal emission from the planet so it is not seen from Earth,” said the study’s lead author, Brice-Olivier Demory of the University of Cambridge’s Cavendish Laboratory.

Demory said the researchers observed “300 percent change in the signal coming from this planet, which is the first time we’ve seen such a huge level of variability in an exoplanet.”

Rick Pantaleo
Rick Pantaleo maintains the Science World blog and writes stories for VOA’s web and radio on a variety of science, technology and health topics. He also occasionally appears on various VOA programs to talk about the latest scientific news. Rick joined VOA in 1992 after a 20 year career in commercial broadcasting.

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