Mysterious heat signature of exoplanet ‘hell world’ – 40 light-years from Earth – could finally be solved by James Webb Space Telescope
For nearly two decades, scientists have been tracking puzzling signals from a huge planet known as ’55 Cancri e.’
The fiery “hell planet” — a so-called super-Earth nearly 40 light-years away — can reach temperatures of more than 4,400 degrees Fahrenheit on its daylight side.
Soon, with help from the James Webb Space Telescope (JWST), researchers hope to be able to fully decode these signals, proving whether or not the planet is fully generating and shedding its own atmosphere under the intense heat of its host star.
As the planet passes by that star, Copernicus, scientists have recorded small eclipses and halos of Copernicus’ own starlight as that light streaks through Cancri e’s hellish atmosphere toward Earth.
A new theory about Cancri e’s evaporating and regenerating atmosphere, published in September, was developed after revisiting data from those eclipses.
The researcher’s new prediction: “a thin, transient, secondary atmosphere” at 55 Cancri e, an atmosphere continually belched out by the ever-present volcanic activity.
The strange infrared heat and visible light signals from the planet are suspected to be the result of an imbalance in Cancri e’s atmosphere, which the JWST will help find answers to
Scientists have revealed that this super-sized planet is a turbulent, volcanic mass of rock that can complete an orbit around its parent star in just 17 hours.
After 55 Cancri e was discovered in 2004, scientists determined that it was likely to contain volcanoes, flowing lava and fast winds with storms of ‘raining’ rock.
Even on the cooler night side, temperatures hover at 55 Cancri e with the sweltering heat of molten rock, about 2060 F.
The planet is “probably so hot,” said Lily Zhao of the Center for Computational Astrophysics at the Flatiron Institute in New York, “that nothing we are aware of could survive on the surface.”
The new study used visible and infrared light collected by three separate space telescopes to model the gaseous composition of this apparently ever-changing atmosphere around 55 Cancri e.
Essentially, the hell planet’s volcanoes are believed to regularly emit hot gas, a process naturally called ‘outgassing’, flooding the entire planet with new layers of atmosphere.
But soon afterward, like clockwork, the sun’s harsh radiation and solar winds strip away much of its extremely hot new atmosphere.
But according to the author of the new study, astrophysicist Kevin Heng from Ludwig Maximilian University in Germany, this churning new atmosphere never leaves the planet completely “bare rocks,” as past theories suggest.
“Despite this variability,” Heng wrote, “the transit depth (the area from the eclipsing planet to its eclipsed star) remains somewhat constant over time and is not consistent with opaque material.”
In other words, even in its most ‘barren’ state, some atmosphere appears to remain, but only visible via an infrared heat signature.
Heng discovered evidence from three orbital telescopes, including the Spitzer Space Telescope and the CHEOPS Space Telescope, that suggested the possibility of a thin, ever-replenishing “secondary atmosphere.”
“As the outgassed atmosphere escapes and is replenished,” Heng wrote, “it rapidly adjusts to the radiative equilibrium and the temperature fluctuations cause the depth of the infrared eclipse to vary.”
Heng’s research – which has been accepted by the journal Astrophysical diary lettersbut not yet peer-reviewed – tested for the presence of several possible gases in Cancri e’s atmosphere to help confirm his hypothesis.
He found that carbon monoxide and carbon dioxide were more likely to occur than methane.
“Atmospheres of pure methane are excluded because they do not produce sufficient Rayleigh scattering,” Heng wrote.
Rayleigh scattering is the time-tested rules for how an atmosphere bends, dampens and generally interacts with light, named after the 19th-century British physicist Lord Rayleigh, who first formulated the principle.
According to past theories about the true hell world, the planet only emits infrared light when there is no gas blanket around 55 Cancri e.
Those scientists had previously predicted that when the atmosphere is present, both the fluctuating visible light and infrared light would contribute to the emitted signal.
But Heng’s theory focused on the evidence from infrared light to explore a proof of concept mathematical model that would allow a thin amount of atmosphere to remain at all times.
Astrophysicists including Heng hope NASA’s JWST can help them measure even more accurately the changes in infrared and visible light coming from the “hell planet” as it passes between Copernicus at the center of its solar system and telescopes here, closer to Earth . .
The ‘hell planet’ is so close to its host star that it completes each new orbit in less than 20 hours, which may also contribute to its unstable environment, but also means many transits and many eclipses from which we need to collect data.
“Upcoming observations with the James Webb Space Telescope,” Heng wrote in his new paper, “will allow atmospheric temperature and surface pressure as well as surface temperature to be measured.”