A new study from a group of researchers including San Francisco State University astronomer Stephen Kane has detailed the first-ever temperature map of a super-Earth planet — a rocky planet outside of our solar system.
The research was published online March 30 in Nature.
The thermal map of 55 Cancri e shows that the planet is very hot but still experiences a strong temperature difference between its dayside and its nightside, suggesting that processes found in planets within our solar system, such as high winds or lava flows, are at work on distant worlds.
The planet is nearly twice the size of Earth but exists under extremely hostile conditions, Kane said, adding that it is so close to its star that an entire year is only 18 Earth hours.
"The planet experiences a vast difference in temperature between its day and the night, so there is almost no thermal communication between the hemispheres," Kane said. "The best explanation for this is that the atmosphere has been completely eroded away by the energy from the star."
Over the past decade, observations have provided key insights into the atmospheres of giant exoplanets, that is, planets located outside the solar system. However, the properties of lower-mass exoplanets remain largely unknown.
"This is the first time such a temperature difference has been observed and gives us extraordinary insights into how atmospheres depend on how close the planet is to the star," Kane said.
Kane and colleagues monitored infrared emissions from the planet with the Spitzer Space Telescope Infrared Array Camera and found that the planet's nightside temperature is around 1,380 kelvin (1,107 degrees Celsius), with the dayside temperature about 1,300 kelvin (1,027 degrees Celsius) hotter at 2,700 kelvin (2,427 degrees Celsius).
The authors also identify a hot spot that they suggest stems from either strong atmospheric winds or low-viscosity lava flows at the planetary surface. They conclude that an additional, currently unknown source of heat is required to explain the observed infrared emission.
"A map of the large day-night temperature gradient of a super-Earth exoplanet" by Brice-Olivier Demory, Michael Gillon, Julien de Wit, Nikku Madhusudhan, Emeline Bolmont, Kevin Heng, Tiffany Kataria, Nikole Lewis, Renyu Hu, Jessica Krick, Vlada Stamenkovic, Bjoern Benneke, Stephen Kane and Didier Queloz was published online in Nature on March 30.