Hot Jupiters: The ‘Roasted Planet’ and the wrong-way hotspot

**Sarah Al-Ahmed** (0:03)
Hot Jupiters, one roasted and one with its hot spot in the wrong place. This week on Planetary Radio.
I'm Sarah Al-Ahmed of the Planetary Society, with more of the human adventure across our solar system and beyond. Coming up, I'm joined by Tiffany Kataria, a research scientist at NASA's Jet Propulsion Laboratory, and Lisa Dang, Assistant Professor at the University of Waterloo, to talk about two hot Jupiter headlines that are straight from the 248th American Astronomical Society meeting. HD 80606b is an eccentric giant that spends most of its year cold and quiet, then gets slammed with flash heating for just a day or two as it swings close to its star. Another exoplanet called CoRoT-2b is a puffed up world whose hottest point shows up in an unexpected location. And after that, we'll check in with our chief scientist, Bruce Betts, for What's Up.
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Now back to our hot Jupiter stories. In June, the American Astronomical Society held its 248th meeting right here in Pasadena. It's one of the biggest gatherings in astronomy. Thousands of scientists, students and educators come together to share their new results. I was there, and I sat in on a press conference called Fire and Ice and Planetary Systems Near and Far, where these two hot Jupiter stories were presented back to back.
The first one, on a planet called HD 80606b, was presented by Dr. Tiffany Kataria. She's a research scientist at NASA's Jet Propulsion Laboratory who focuses on atmospheric dynamics and chemistry. HD 80606b is about 217 light-years away in the constellation of Ursa Major. It's a giant planet that's roughly four times the mass of Jupiter, and it orbits a sun-like star every 111 days. But what makes this world extraordinary is its eccentricity. It's one of the most extreme orbits of any known exoplanet. At its farthest, it's about as far from its star as Venus is from our sun. But at its closest, it's ten times closer than Mercury.
Earlier observations with the Spitzer Space Telescope gave us our first look at this world's atmosphere. But Tiffany's team has now captured new data using the MIRI instrument on the James Webb Space Telescope. MIRI looks in the mid-infrared, and it's a data set that was years in the making, as you'll hear in this conversation. There's also a separate set of JWST observations using the NIRSPEC instrument from another team. That's in the near-infrared. And combining these two data sets promises an even richer picture of what's going on with this world. And you may have actually seen this exoplanet before without knowing it. HD 80606b is the Roasted Planet from NASA's Galaxy of Horrors poster series, and it honestly earns that name. I walked out with one of those posters myself, and now I'm just looking for a place to frame it in my apartment. Our second story today is on Coro-2b, which was presented by Dr. Aurora Caselli. Aurora is currently on maternity leave, so I want to send a huge congratulations to her and her family. Dr. Lisa Dang is going to be joining us in her place. Both Lisa and Aurora were co-authors on a paper called Unraveling the Mystery of the Peculiar and Young Hot Jupiter Coro-2b, which was published in the Astronomical Journal. Lisa is an assistant professor at the University of Waterloo, who studies hot Jupiter atmospheres and lava planets. Coro-2b was discovered back in 2007 by the French-led Coro spacecraft, and sits about 700 light-years away in the constellation of Aquila. It orbits a young, active, sun-like star, and completes a full orbit in just 1.7 days. It's about 3.3 times Jupiter's mass, but 1.4 times Jupiter's radius. So, Coro-2b is noticeably inflated. Lisa first mapped this planet's thermal emissions using the Spitzer Space Telescope, and the paper that Aurora presented uses ground-based, high-resolution spectroscopy from the Gemini South Telescope to dig further into its atmosphere. Most hot Jupiters on orbits that tight are expected to be tidally locked, but Coro-2b's hotspot shows up in a completely unexpected place, which may mean that this young world hasn't fully tidally locked to its star yet. These two planets are striking examples of just how different hot Jupiters can be from one another.