A recent discovery in the field of astrophysics has left scientists puzzled: the planet WASP-193b, a gas giant, has such a low density that it is compared to cotton candy. Located about 1,200 light-years from Earth, this exoplanet orbits a star similar to the Sun.
Of course, the planet isn't actually made of cotton candy!
What particularly distinguishes this planet is its extremely low density. Although WASP-193b is about 50% larger than Jupiter, it has only one-seventh of Jupiter's mass, classifying it among the least dense planets ever observed. This discovery, made by a team of researchers from the EXOTIC Laboratory at the University of Liège in Belgium, in partnership with MIT and the Institute of Astrophysics of Andalusia, challenges current theories of planet formation.
The detection of WASP-193b was made possible by the WASP project, which uses two robotic observatories to monitor stars. The collected data showed periodic transits of the star WASP-193, revealing the presence of this planet orbiting it. To validate this discovery, the researchers used the TRAPPIST-South and SPECULOOS-South observatories in Chile to measure the planet's signal in different wavelengths. Spectroscopic observations then allowed them to determine the mass of WASP-193b.
The results were astonishing: the planet's density was extremely low, about 0.059 grams per cubic centimeter, compared to 1.33 grams per cubic centimeter for Jupiter and 5.51 grams per cubic centimeter for Earth. The planet is primarily composed of hydrogen and helium, forming an extremely swollen atmosphere that extends far beyond that of Jupiter.
Current models fail to explain how a planet can accumulate such an extended and light atmosphere. The usual mechanisms seem insufficient to explain the extent of the expansion observed in WASP-193b. This discovery opens up exciting new prospects for exoplanet research but also raises questions about the diversity and complexity of worlds beyond our solar system.
Article author: Cédric DEPOND