A planet 1.5x Jupiter’s size but lighter than styrofoam discovered 1,181 light-years away.
Key Takeaways
- Astronomers have discovered WASP-193b, a planet with a density similar to cotton candy.
- This gas giant is 50% larger than Jupiter but 7 times less dense.
- WASP-193b defies standard planet formation theories due to its unusually low density.
- The planet orbits its star every 6.2 days, at just 7% of Earth’s sun distance.
- Researchers aim to study its hydrogen-helium atmosphere further, using tools like JWST.
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WASP-193b: The Cotton Candy Planet
Astronomers have discovered one of the least dense planets ever found, WASP-193b, located about 1,181 light-years from Earth. With a density of just 0.059 grams per cubic centimeter—comparable to cotton candy—this gas giant is 50% larger than Jupiter yet seven times less dense. Its discovery, detailed in Nature Astronomy, challenges current models of planet formation and evolution.
The planet orbits a star similar in size to the sun once every 6.2 days, at a distance only 7% of that between Earth and the sun. Despite its low mass of 0.139 Jupiters, its radius is 1.5 times that of Jupiter, making it an anomaly. Co-author Julien de Wit from MIT described the planet as “super fluffy,” with a structure primarily consisting of hydrogen and helium gases.
A Cosmic Puzzle
WASP-193b’s extreme lightness places it as the second-least dense planet discovered, after Kepler-51d. Unlike similar planets, whose atmospheres are typically stripped away by stellar winds, this one retains its extended atmosphere for reasons not yet understood. Khalid Barkaoui of the University of Liège’s EXOTIC Laboratory explained that standard models of irradiated gas giants fail to explain its formation.
First identified in 2023 by the Wide Angle Search for Planets (WASP) project, the planet’s existence was inferred from periodic dips in its star’s brightness, caused by its transit. Researchers believe its low density could be linked to an unusually inflated atmosphere, yet the mechanism behind such inflation remains unclear.
Astronomers hope future observations, particularly with the James Webb Space Telescope (JWST), will provide more insights into WASP-193b’s atmosphere and evolutionary history. Study co-author Francisco Pozuelos emphasized the need to study its properties further to uncover how such a planet could form and persist.
WASP-193b’s discovery not only enriches our catalog of exoplanets but also highlights the limitations of current planetary science theories, presenting an exciting mystery for astronomers to unravel.
