|An artist's depiction of the exoplanet 55 Cancri E with its molten surface exposed on the left, and covered in gas and ash on the right. (NASA/JPL - Caltech/R.Hurt)|
Excerpt from latimes.com
Scientists have found an extreme planet where the atmospheric temperature appears to swing wildly from 1,800 to 4,900 degrees Fahrenheit over the course of a two-year period.
Astronomers cannot yet say for certain what might be responsible for these drastic shifts in temperature, but in a new study, they suggest massive volcanoes on the planet's surface may be to blame.
"While we can't be entirely sure, we think a likely explanation for this variability is large-scale surface activity, possibly volcanism," said Brice-Olivier Demory of the University of Cambridge in a statement.
Demory is the lead author of a paper that describes how the gas and dust in enormous volcanic plumes might periodically blanket the thermal emission of the planet as seen from Earth, making its atmosphere appear cooler to our telescopes.
The study was published Monday in the Monthly Notices of the Royal Astronomical Society.
The extreme planet is known as 55 Cancri E. It is a super-Earth, which means it is both rocky and two to 10 times the size of our own planet. 55 Cancri E has about twice the diameter of Earth, but it has eight times the mass. It is also tidally locked with its star which means it has one side that stays in perpetual day, and another that remains in perpetual night.
It was discovered in 2004 and was the first rocky planet to ever be seen beyond our solar system. Up until then all the known exoplanets were gas giants that were easier to spot because they are so enormous -- up to 300 times the size of Earth.
55 Cancri E lies uncomfortably close to its host star (by our standards) and takes just 18 days to complete a single orbit around its sun.
Because the planet is so hot even on its seemingly cooler days, its outermost shell is likely weakened, if not entirely molten, the researchers say. This could lead to magma oceans and the strong likelihood of volcanic activity.
However, it will take more time, more observations, and potentially more sensitive equipment to know for sure what is going on.
"The present variability is something we've never seen anywhere else, so there's no robust conventional explanation," said Nikku Madhusudhan of Cambridge's Institute of Astronomy and a co-author of the study in a statement.