A team of scientists from the University of Cambridge in the UK and the University of Liege in Belgium has detected changing temperatures on a terrestrial exoplanet known as 55 Cancri e, and believe it could be due to large amounts of volcanic activity.
55 Cancri e is so close to its host star that it must experience extreme conditions. Image credit: ESO / L. Calçada.
55 Cancri e was discovered on August 30, 2004. It has a radius twice Earth’s, and a mass 8 times greater, making it a so-called super-Earth.
It is one of five planets orbiting the Sun-like star 55 Cancri A that is located 40 light-years away yet visible to the naked eye in the constellation of Cancer.
The planet orbits its host star at a distance of 0.015 AU – about 25 times closer than Mercury is to our Sun – every 18 hours.
55 Cancri e is also tidally locked, meaning that it doesn’t rotate like our planet does – instead there is a permanent ‘day’ side and a ‘night’ side.
The astronomers from the United Kingdom and Belgium for the first time found rapidly changing conditions on the planet, with temperatures on the hot ‘day’ side swinging between 1,800 and 4,900 degrees Fahrenheit (1,000 – 2,700 degrees Celsius). They used NASA’s Spitzer Space Telescope to observed thermal emissions coming from 55 Cancri e.
“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. No signature of thermal emissions or surface activity has ever been detected for any other super Earth to date,” said Dr Nikku Madhusudhan of the University of Cambridge, a co-author on the paper submitted to the Monthly Notices of the Royal Astronomical Society (arXiv.org preprint).
Dr Madhusudhan and co-authors believe the variability in temperature could be due to huge plumes of gas and dust which occasionally blanket the surface, which may be partially molten.
The plumes could be caused by exceptionally high rates of volcanic activity, higher than what has been observed on the Galilean moon Io.
“We saw a 300% 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,” said Dr Brice-Olivier Demory of Cavendish Laboratory, lead author of the new study.
“While we can’t be entirely sure, we think a likely explanation for this variability is large-scale surface activity, possibly volcanism, on the surface is spewing out massive volumes of gas and dust, which sometimes blanket the thermal emission from the planet so it is not seen from Earth.”
_____
Brice-Olivier Demory et al. 2015. Variability in the super-Earth 55 Cnc e. Mon. Not. R. Astron. Soc., submitted for publication; arXiv: 1505.00269
