The planets entitled “Super Hot Earths” can be particularly bright for scientists watching them and researchers have already assumed that this striking feature is because starlight reflects off the vast oceans of lava and glass present on the surface of these exoplanets. However, the reason for so much brightness may be another.
Hot Super Earths are scaly, rocky exoplanets, smaller than gas giants, located close to their stars and displaying a relatively fine atmosphere. However, they are huge compared to our Earth, being two to ten times larger.
In a study published in the scientific journal Astrophysical Journal, scientists from the Massachusetts Institute of Technology (MIT) suggest that hot Super Earths are so bright thanks to reflective clouds that form in their metal-rich atmospheres.
Simulation of the surface and atmosphere of a hot Super Earth. Image: iStock
Although the hypothesis of the oceans of lava and glass was widely accepted, there was no evidence to support it. It was then that MIT researchers built miniatures of hot Super Earths by melting rocks in the laboratory to calculate how bright the lava and glass would look. The result was scorching balls proportionally less brilliant than expected compared to the glow emitted by real exoplanets.
“We are not 100% sure what these planets are made of, so we are narrowing the space of the parameters and guiding future studies for all these other potential options,” explained Zahra Essack, an MIT student who worked on the research.
The study conducted by MIT scientists also did not provide evidence for the existence of metal-rich clouds, but it suggested that there must be something else behind the abnormal luminosity of the hot Super Earths – and the atmosphere seems to be a good way to find out why .
“We still have a lot to understand about these lava ocean planets,” said Essack. “We think of them only as shiny rock balls, but these planets can have complex systems of very exotic surface and atmospheric processes, and it’s not something we’ve seen before,” he added.
MIT Exoplanets Science & Space Super Earth