WASP-193b, a new exoplanet, is 50% larger than Jupiter but seven times less massive, with an extremely low density similar to cotton candy. Discovered by WASP and confirmed by observatories in Chile, its formation challenges current planetary theories and requires further study. Posted by SciTechDaily.com
this an exoplanet larger, but seven times less massive Jupiter and is the second least dense planet discovered to date.
An international team led by researchers from the EXOTIC Laboratory of the University of Liège in collaboration with MIT and the Institute of Astrophysics in Andalusia have just discovered WASP-193b, an extremely low-density giant planet orbiting a distant Sun-like star.
The newly discovered planet, located approximately 1,200 light-years from Earth, is 50% larger than Jupiter, but seven times less massive. This causes it to have an extremely low density, comparable to that of cotton candy.
“WASP-193b is the second lowest-density planet discovered to date, after Kepler-51d, which is much smaller,” explains Khalid Barkaoui, a postdoctoral researcher at the EXOTIC ULiège Laboratory and first author of the paper published in Astronomy of nature. Its extremely low density makes it a true anomaly among the more than five thousand exoplanets discovered to date. This extremely low density cannot be reproduced by standard models of irradiated gas giants, even under the unrealistic assumption of a coreless structure.”
Initial discoveries and observations
The new planet was initially spotted by the Wide Angle Search for Planets (WASP), an international collaboration of academic institutions that jointly operate two robotic observatories, one in the Northern Hemisphere and the other in the Southern Hemisphere. Each observatory used many wide-angle cameras to measure the brightness of thousands of individual stars across the sky.
In data obtained between 2006 and 2008 and again from 2011 to 2012, the WASP-South observatory detected periodic transits or dips of light from the star WASP-193. Astronomers determined that the star’s periodic dips in brightness correspond to the planet passing in front of the star every 6.25 days. Scientists measured the amount of light the planet blocked at each transit, which gave them an estimate of the planet’s size.
Artist’s impression of the density of WASP-193b compared to cotton candy. Author: University of Liège
Detailed measurements and amazing density
The team then used the TRAPPIST-South and SPECULOOS-South observatories, led by Michael Guion, director of research at FNRS and an astrophysicist at ULiège, located in the Atacama Desert in Chile, to measure the planetary signal at different wavelengths and confirm the planetary nature of the planet. an obscuring object. Finally, they also used the spectroscopic observations collected HARPS and CORALIE spectrographs – also located in Chile (ESO)- to measure the mass of the planet.
Much to their surprise, the accumulated measurements revealed an extremely low density of the planet. Its mass and size, according to their calculations, were about 0.14 and 1.5 Jupiter masses, respectively. The resulting density was about 0.059 grams per cubic centimeter.
Jupiter’s density, by contrast, is about 1.33 grams per cubic centimeter; and Earth a more substantial 5.51 grams per cubic centimeter. One of the materials closest in density to the new chubby planet is cotton candy, which has a density of about 0.05 grams per cubic centimeter.
The secret of the composition of WASP-193b
“The planet is so light that it is difficult to come up with an analogous solid-state material,” says Julien de Wit, a professor at the Massachusetts Institute of Technology (MIT) and a co-author. “The reason it’s close to cotton candy is that both are largely air. The planet is mostly very fluffy.’
Researchers suspect that the new planet is composed mostly of hydrogen and helium, like most other gas giants in the galaxy. For WASP-193b, these gases likely form a highly inflated atmosphere that extends tens of thousands of kilometers further than Jupiter’s own atmosphere. How exactly a planet can inflate so much is a question that no existing theory of planet formation can yet answer. Of course, this requires a significant supply of energy deep within the planet, but the details of the mechanism are not yet clear.
Future research and challenges
“We don’t know where to put this planet in all the formation theories we have now because it’s an outlier from all of them. We cannot explain how this planet was formed. A closer study of its atmosphere will allow us to constrain the evolutionary path of this planet, adds Francisco Posuelos, an astronomer at the Institute of Astrophysics of Andalusia (IAA-CSIC, Granada, Spain).”
“WASP-193b is a cosmic mystery. Resolving this will require further observational and theoretical work, in particular to measure its atmospheric properties with the JWST space telescope and compare them to the various theoretical mechanisms that possibly lead to such extreme inflation,” concludes Khalid Barkaoui.
For more information on this discovery, see Super Fluffy “Cotton Candy” Exoplanet Discovery Shocks Scientists.
Reference: “Extended low-density atmosphere around the Jupiter-sized planet WASP-193 b” by Khalid Barkaoui, Francisco J. Posuelos, Coel Helier, Barry Smalley, Louise D. Nielsen, Prajwal Niraula, Michael Guion, Julien de Witt, Simon Muller, Caroline Dorn, Ravit Heled, Emmanuel Jehin, Brice-Olivier Demory, Valerie Van Grotel, Abderrahman Soubkiu, Murad Gachoui, David. R. Anderson, Zuhair Benhaldoun, Francois Bouchy, Artem Bourdanov, Letizia Delrez, Elsa Ducrot, Lionel Garcia, Abdelhadi Jabiri, Monica Lendl, Pierre F. L. Maxtedt, Catriona A. Murray, Peter Pilman Pedersen, Didier Keloz, Daniel Sebastian, Oliver Turner, Stefan Udry, Matilda Zimmermans, Amari H.M.J. Trio and Richard G. West, May 14, 2024. Astronomy of nature.
DOI: 10.1038/s41550-024-02259-y