A scientific team has managed to obtain valuable information about a particular category of exoplanets. The James Webb Space Telescope has in fact provided the clearest images so far of this mysterious celestial body, called “mini-Neptune” by scientists. Let’s see together what they discovered.
After carefully observing the belts around Fomalhaut, the JWST has now succeeded in analyzing the planet GJ 1214 b; according to the data, this world would appear to be covered by a very reflective dense atmosphere. Although it is too hot to have oceans, it may still have water in the form of vapor.
“The planet is totally covered by a sort of haze or cloudy layer,said Eliza Kempton, a researcher at the University of Maryland.The atmosphere had remained entirely hidden from our view until now.”
To succeed in penetrate this thick barrier and looking inside the exoplanet, the team tried a new approach: in addition to using standard observation (capturing the star’s light filtered through the atmosphere), they tracked GJ 1214 b almost its entire orbit around its star .
The success of the observation once again demonstrates the effectiveness of the Mid infrared instrument (MIRI) aboard the JWST, capable of seeing light outside the electromagnetic spectrum we know. In this way, the telescope was able to create a sort of “heat map” of the planet.
“Capturing a full orbit was crucial to understanding the heat distribution from the day side to the night side.Kempton explained. “There is a great contrast between day and night. The night side is much colder.” The temperature of the planet goes from 279°C to 165°C.
This contrast is possible only in an atmosphere composed of heavy molecules, such as water and methane. This can be a big clue to planet formation; according to the researcher, “this is not a primeval atmosphere. It does not reflect the composition of its star. Rather it may have lost a lot of hydrogen over time, or had a lot of heavy elements to begin with – water and ice.“
Further observations will be needed in the future to obtain more details on the formation of the celestial body, and to discover more about this mysterious class of “mini-Neptunian” exoplanets.