Scientists discover a giant planet that’s light and fluffy like cotton candy

The galaxy can sometimes give rise to some strange surprises, but an exoplanet discovered 1,232 light-years away is one of the strangest yet. It’s WASP-193b, and despite being nearly 50% larger than Jupiter, it’s so light and fluffy that its overall density is comparable to cotton candy. This is just a hair, which is more than 1 percent of the density of the Earth. It really is the world’s dandelion balls…if dandelion balls could become planets. Exoplanets like WASP-193b are rare, but not uncommon, and could help us better understand planetary evolution, according to an international team led by astronomer Khaled Barkaoui from the University of Liège in Belgium. It is said that there is. “WASP-193b is the second least dense planet ever discovered, after the much smaller Kepler-51d,” Barkaoui explains. “Its extremely low density makes it a true anomaly among the more than 5,000 exoplanets discovered to date. This extremely low density is due to the unrealistic assumption of a coreless structure. But it cannot be reproduced using standard models of irradiated gas giant planets.” Seeing all the weird and wonderful worlds out there not only helps us understand the situation in our solar system, but also provides insight into the formation and evolution of planetary systems.

Gas giant planets near stars are excellent tools for this, because based on our understanding of planet formation, they must have formed elsewhere and migrated inward. Additionally, stellar radiation also shrinks many of these worlds. WASP-193b is an exoplanet orbiting a sun-like star called WASP-193. This star has about 1.1 times the mass of the Sun, a radius 1.2 times hers, and is very close in temperature and age to the Sun. However, WASP-193b orbits the star much closer than any other planet in our solar system, completing one orbit around her every 6.25 days. By studying how starlight changes as exoplanets orbit, Barkaoui and his colleagues were able to calculate the world’s radius and mass. Its radius is about 1.46 times the radius of Jupiter. However, its mass is incredibly small by comparison, only 0.139 times the mass of Jupiter. From these properties, the researchers derived the exoplanet’s density: 0.059 grams per cubic centimeter. For comparison, Earth’s density is 5.51 grams per cubic centimeter. Jupiter’s density is 1.33 grams per cubic centimeter, which is not surprising – there are a lot of clouds. The density of cotton candy is 0.05 grams per cubic centimeter. “This planet is so light that it’s hard to imagine anything similar in solid matter,” said Julian de Witt, a planetary scientist at the Massachusetts Institute of Technology. “They’re similar to cotton candy because they’re both essentially made of air. This planet is basically very fluffy.” Few other worlds with comparable density have been found, but they provide some clues as to how such fluffy worlds arise. As it approaches a star, its atmosphere can heat up and expand, especially if the atmosphere is made up primarily of hydrogen and helium. But such a world will only look like her WASP-193b for tens of millions of years or so, when stars become younger and hotter. Additionally, the star’s heat and winds can destroy such a fragile atmosphere fairly quickly. Therefore, several problems arise. This star is thought to be up to 6 billion years old. Although a mechanism for WASP-193b’s atmosphere to expand due to internal heat may exist, the observed exoplanet properties cannot be reproduced using sophisticated planetary evolution models. “WASP-193b is a cosmic mystery. Further observational and theoretical work is needed to resolve this,” says Barkaoui.

source: https://dx.doi.org/10.1038/s41550-024-02259-y