Orbit of newly discovered exoplanet TOI-3261 (also known as TIC 358070912) is an inactive main sequence star located 300 parsecs (978.5 light years) away in the constellation Hydra.
Artist's concept of the super-hot Neptunian exoplanet TOI-3261b. Image credit: NASA/JPL-Caltech/K. Miller, Caltech & IPAC.
The radius of this newly discovered exoplanet, named TOI-3261b (TIC 358070912b), is 3.82 Earth's radius.
Its mass is 30.3 times that of Earth, more than twice the median mass of Neptune-sized planets in longer orbits.
To determine these properties, astronomer Emma Nabby from the University of Southern Queensland and her colleagues used data from NASA's Exoplanet Survey Satellite (TESS), the Las Cumbres Observatory's Global Telescope, and the ESPRESSO and HARPS instruments. I used
“In our measurements, TOI-3261b is exactly hot neptune desert “The planets are so rare that their rarity evokes images of desolate landscapes,” the astronomers said in a statement.
“This type of exoplanet is similar in size and composition to our own Neptune, but it orbits very close to its star.”
The planet orbits its parent star, TOI-3261, every 21 hours.
Such a narrow orbit has so far allowed the planet to belong to the same group as only three other ultrashort-period, high-temperature Neptunes: LTT-9779b, TOI-849b, and TOI-332b.
“TOI-3261b has proven to be an ideal candidate for testing new computer models of planet formation,” the researchers said.
“One reason hot Neptunes are so rare is that it's difficult to maintain a thick gaseous atmosphere in the immediate vicinity of the star.”
“Because stars are massive, they exert a large gravitational force on surrounding objects and can strip away layers of gas surrounding nearby planets.”
“It also releases a lot of energy and blows away the gas layer.”
“Both of these factors mean that a hot Neptune like TOI-3261b may have started out as a much larger Jupiter-sized planet and then lost most of its mass.”
The TOI-3261 system is about 6.5 billion years old, and the planet began as a much larger gas giant, the researchers said.
“But it likely lost mass in two ways: by photoevaporation, where energy from the star causes gas particles to dissipate, and by gravity from the star, which strips layers of gas from the planet. tidal separation,” the scientists said.
“It's also possible that the planet formed further away from the star, where both of these effects would be less strong and it would be able to maintain an atmosphere.”
“The planet's remaining atmosphere is one of its most interesting features and will likely invite further atmospheric analysis, perhaps helping to elucidate the formation history of this hot Neptunian desert dweller.”
“TOI-3261b's density is about twice that of Neptune, indicating that the lighter parts of the atmosphere have been removed over time, leaving only the heavier components,” the researchers added.
“This suggests that the planet must have started out with a variety of elements in its atmosphere, but at this stage it's difficult to know exactly what they are.”
This finding is reported in the following article: paper Published in astronomy magazine.
_____
Emma Naby others. 2024. Survival in the Hot Neptunian Desert: Discovery of the ultrahot Neptune TOI-3261b. A.J. 168, 132; doi: 10.3847/1538-3881/ad60be
Source: www.sci.news
