A group of astronomer and citizen scientists have discovered a planet the size of Jupiter in a distant solar system and should get to see it again soon.
The planet, named TOI-2180 b, is very close to us here on Earth. It takes a giant exoplanet a long time to get to its host star, which is much longer than most gas giants discovered outside of our solar neighborhood.
The team spotted the world using data from NASA's TESS. TESS spots exoplanets by finding small dips in a star's brightness that are caused by a planet blocking a little bit of the star's light as it transits or passes between the spacecraft and the star. Scientists think TESS will see the planet again in February.
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There are some good videos for you. It was created with a sketch.
"Transit events are the best avenue to discover cooler exoplanets," said Paul Dalba, the study lead author, during a news conference about the discovery at the American Astronomical Society's 239th meeting on Thursday.
Dalba said it was cool because of how unique the exoplanet is, but also because of its lower temperature caused by its longer-period orbit around its parent star. The presentation can be seen in the video at the beginning of the 34 minute mark.
Dalba said there was a lot of science motivation behind studying long-orbit exoplanets. We can ask about the evolution of exoplanets and whether they form differently. How do they change over time?
Jupiter is roughly the same size as TOI-2180 b. The University of New Mexico, the home institution of discovery team member Diana Dragomir, issued a release stating that the planet contains 105 Earth mass elements heavier than hydrogen and helium. The density difference could be a sign that the planet formed differently than Jupiter.
The planet's temperature is 170 degrees Fahrenheit, which is surprisingly mild. TOI-2180 b is not as warm as Jupiter or Saturn, but it is still quite chilly. Many of the gas giant exoplanets found to date are close-orbiting "hot Jupiters," which are easier to find because they transit more often and exert a greater pull on their host stars than do planets that are farther away.
"It's a nice stepping stone in between the giant exoplanets we've found and the cold Jupiter and Saturn," Dalba said in a NASA press release. The temperature difference is not yet understood, but could be explored with observations from other telescopes.
An artist's depiction of NASA's TESS in space. The image was taken at NASA's Goddard Space Flight Center.
Tom Jacobs, a former U.S. naval officer, was part of the team that made the discovery. Jacobs is a participant in Planet Hunters, a NASA-funded citizen science project run through the online platform Zooniverse that focused on data from NASA's now-retired Kepler planet-hunting spacecraft.
Jacobs said that the discovery and publication of TOI-2180 b was a great group effort demonstrating that professional astronomer and seasoned citizen scientists can successfully work together.
The team of citizen scientists and astronomer collaborated to look at TESS data. The planet's parent star had a dip in brightness. Astronomers Dalba and Dragomir were notified by Jacobs since stellar brightness fluctuations can be caused by sunspots.
The team received more information from observations by the Automated Planet Finder Telescope at Lick Observatory in California and the W. M. Keck Observatory in Hawaii. The team was able to zero in on the mass of the planet after seeing the tug of the planet on its parent star.
The planet's position is still uncertain. The team used telescopes to look for a transit at 14 sites across three continents in August 2020.
55 datasets were produced in 11 days, but no telescope caught the transit. NASA said that the lack of information allowed them to put a boundary on the time.
Scientists hope to study TOI-2180 b further to look for rings or moons, which are common among gas giants in our own solar system. Most big exoplanets have been found very close to their parent stars, where the intense gravity may rip things like rings away from the planet. The TOI-2810b may be a fun system to look for moons or rings since it is farther from its star.
The study was published in the journal.
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