Exoplanetary Atmosphere Categorization Begins

Apr 28, 2022 | Daily Space, Exoplanets

Exoplanetary Atmosphere Categorization Begins
IMAGE: Artist’s conceptual image of the 25 exoplanets examined in this study. CREDIT: ESA/Hubble, N. Bartmann

Not every world we talk about in this show is, of course, in our own solar system. There are over 5,000 confirmed exoplanets out there in our galaxy, and every day, we learn more and more about them. The trend these days is pushing the field of exoplanetary atmosphere categorization in amazing directions, what with advances to ground-based telescopes, new uses of space telescopes, and even, maybe, possibly (I am really tired of waiting) a new space telescope.

And this week, researchers released a new paper in The Astrophysical Journal Supplement Series that presented a catalog of 25 exoplanets observed using hundreds of hours of observing time on both the Hubble and Spitzer space telescopes. Those 25 worlds are all considered hot Jupiters – those gas giants that orbit very close to their parent stars, heating up to wild temperatures.

Awesomely, the team found common threads among the properties they analyzed, including thermal profiles and chemical abundances. For one characteristic, they look at “thermal inversion”, where an atmosphere that generally traps heat has a temperature that increases as you get deeper into that atmosphere…until it doesn’t increase. So sometimes, there might be a layer that is warmer than the layer below. Ozone does that here on Earth.

Of the hot Jupiters that had a thermal inversion layer, there was also evidence for hydrogen anions and metallic oxides. And then the planets that didn’t have an inversion layer also didn’t tend to have those chemicals. While correlation doesn’t equal causation, those metallic components are really good at absorbing stellar light, which would increase the temperature around those compounds.

Just one more paper bringing us closer and closer to understanding planetary formation. Exciting times are ahead, everyone.

More Information

ESA Hubble press release

NAOJ press release

Five Key Exoplanet Questions Answered via the Analysis of 25 Hot-Jupiter Atmospheres in Eclipse,” Q. Changeat et al., 2022 April 25, The Astrophysical Journal Supplement Series


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