![]() ![]() Such a pronounced swing in temperature indicates that heavy molecules are present, like H 2O and CH 4. The image also indicates that the planet reflects a significant amount of the incident starlight it receives. The black region is a data processing drop out. The night side is colder than the day side.” The temperatures shifted from 279 to 165 C (535 to 326 degrees F.) This figure from the study is a global heat map of exoplanet GJ 1214b. “There’s a lot of contrast between day and night. “The ability to get a full orbit was really critical to understand how the planet distributes heat from the day side to the night side,” Kempton said. Its observations created a heat map of the planet that showed both day and night sides, illuminating more details of its atmosphere. The JWST’s powerful MIRI instrument was brought to bear on the planet as it orbited its star. But in this case they followed the planet through almost an entire orbit. The starlight passes through the atmosphere and the light is analyzed to sense chemical constituents and other characteristics. Ordinarily, astronomers train telescopes on an exoplanet as it transits in front of its star. Kempton and her co-authors went beyond a typical exoplanet observation. “The atmosphere just remained totally hidden from us until this observation.” “The planet is totally blanketed by some sort of haze or cloud layer,” said lead author Kempton. Considering all this, it makes sense that astronomers wanted to use the JWST to study it further. ![]() But any further detail was hidden by the planet’s thick layer of haze or clouds. It was the first mini-Neptune found that has an atmosphere, and only the second one where the mass and radius were determined. The atmosphere is probably escaping hydrodynamically, indicating that it has undergone significant evolution during its history.” In the paper presenting its discovery, the authors wrote “We find that the planetary mass and radius are consistent with a composition of primarily water enshrouded by a hydrogen-helium envelope that is only 0.05% of the mass of the planet. It’s about eight times more massive than Earth, and about 2.75 Earth radii. Follow-up observations with the Hubble suggested it was a waterworld with a thick, steamy atmosphere. The MEarth Project found GJ 1214 b, its only planet, with the transit method in 2009. Gliese 1214 is a red dwarf star about 40 light years away in the Ophiuchus constellation. Aldaron – Own work, incorporating public domain images for reference planets (see below), inspired by Thingg’s size comparison, CC BY-SA 3.0, As this image shows, GJ 1214 b is intermediate in size between Earth and Neptune. Mini-Neptunes are sometimes called Super-Earths. That judicious process led one team of astronomers to GJ 1214 b (Gliese 1214 b.) They observed the mini-Neptune with the JWST’s MIRI and Low-Resolutions Spectrometer and published their results in a paper in Nature titled “A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve.” The lead author is Eliza Kempton, a researcher at the University of Maryland. But with so many exoplanets begging to be studied, astronomers using the JWST have to choose their targets judiciously. ![]()
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