Kempton noted that while the planet is hot by human standards, it is much cooler than expected. This is because, to the researchers’ surprise, its unusually bright atmosphere reflects much of the light from its parent star rather than absorbing and warming it.
The new observations could open the door to deeper knowledge of what kind of planet is shrouded in uncertainty. Mini-Neptunes — or sub-Neptunes as they’re called in the paper — are the most common type of planet in the galaxy, but mysterious to us because they don’t occur in our solar system. Measurements so far show that it looks a lot like, say, a miniature copy of our own Neptune. Beyond that, little is known.
“For about the past decade or so, the only thing we really knew about this planet was that its atmosphere was cloudy or hazy,” said Rob Zelm, an exoplanet researcher who works with co-author and exoplanet research fellow Tiffany Kataria at NASA’s Jet Propulsion Laboratory. “. in Southern California. “This paper has really impressive implications for additional detailed climate explanations — for looking at the detailed physics that’s going on inside this planet’s atmosphere.”
The new work indicates that the planet may have formed far from its star, a type known as a red dwarf, and then spiraled gradually inward to its current, close orbit. A planet’s year – one orbit around the star – takes only 1.6 Earth days.
“The simplest explanation, if you find a planet very rich in water, is that it formed far from the host star,” Kempton said.
Further observations will be needed to determine more details about GJ 1214 b as well as the formation dates of the other planets in the minor Neptune class. While a watery atmosphere seems likely for this planet, a significant component of methane is also possible. Drawing broader conclusions about how mini-Neptunes formed will require observing more of them in depth.
“By observing a whole bunch of things like this, we hope we can build a consistent story,” Kempton said.
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