Jan. 15 () –
Observations from the James Webb Space Telescope and simulation models have confirmed, 48 light years away, a new type of planet different from anything found in the Solar System.
To date, more than 5,000 exoplanets have been confirmed around stars other than the Sun. Many exoplanets are different from any of the planets in the Solar System, making it difficult to guess their true nature. One of the most common types of exoplanets is found in a size range between Earth and Neptune. Astronomers have debated whether these planets are rocky Earth-like planets with thick hydrogen-rich atmospheres, or icy Neptune-like planets surrounded by water-rich atmospheres, called water worlds.
Previous studies have been confounded by high, thick cloud layers, which seem to be common on this type of planets, and make it difficult to study the atmosphere below the cloud layer.
An international team of researchers led by Everett Schlawin of the University of Arizona and Steward Observatory and Kazumasa Ohno of the National Astronomical Observatory of Japan (NAOJ) used the James Webb Space Telescope to observe through the clouds an example of this type of exoplanet known as GJ 1214 b. Located just 48 light years from the Solar System, towards the constellation Ophiuchus, GJ 1214 b is the easiest example of this planet to study.
CARBON-DOMINATED ATMOSPHERE, LIKE A “SUPER-VENUS”
Instead of a hydrogen-rich super-Earth or a water world, the new data revealed carbon dioxide (CO2) concentrations comparable to levels found in the dense CO2 atmosphere of Venus in the Solar System. But there were still many uncertainties in the new data.
“The CO2 signal detected in the first study is minuscule, so careful statistical analysis was required to ensure it was real,” explains Ohno. in a statement. “At the same time, we needed physical and chemical knowledge to extract the true nature of GJ 1214 b’s atmosphere from Schlawin’s study.” So Ohno took the lead, using theoretical models to run a plethora of hypothetical scenarios about the planet’s atmosphere. Of all these models, the ones that best fit the data suggest a carbon-dominated atmosphere, like a “super-Venus.”
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