Astronomers Spot A Giant Planet That Is As Li | EurekAlert!

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Astronomers at MIT, the University of Li⁘ge in Belgium, and elsewhere have discovered a huge, fluffy oddball of a planet orbiting a distant star in our Milky Way galaxy. The discovery, reported today in the journal Nature Astronomy , is a promising key to the mystery of how such giant, super-light planets form.

The new planet, named WASP-193b, appears to dwarf Jupiter in size, yet it is a fraction of its density. The scientists found that the gas giant is 50 percent bigger than Jupiter, and about a tenth as dense ⁘ an extremely low density, comparable to that of cotton candy.

WASP-193b is the second lightest planet discovered to date, after the smaller, Neptune-like world, Kepler 51d. The new planet⁘s much larger size, combined with its super-light density, make WASP-193b something of an oddity among the more than 5,400 planets discovered to date.

⁘To find these giant objects with such a small density is really, really rare,⁘ says lead study author and MIT postdoc Khalid Barkaoui. ⁘There⁘s a class of planets called puffy Jupiters, and it⁘s been a mystery for 15 years now as to what they are. And this is an extreme case of that class.⁘

⁘We don⁘t know where to put this planet in all the formation theories we have right now, because it⁘s an outlier of all of them,⁘ adds co-lead author Francisco Pozuelos, a senior researcher at the Institute of Astrophysics of Andalucia, in Spain. ⁘We cannot explain how this planet was formed, based on classical evolution models. Looking more closely at its atmosphere will allow us to obtain an evolutionary path of this planet.⁘

The study⁘s MIT co-authors include Julien de Wit, an assistant professor in MIT⁘s Department of Earth, Atmospheric and Planetary Sciences, and MIT postdoc Artem Burdanov, along with collaborators from multiple institutions across Europe.

The new planet was initially spotted by the Wide Angle Search for Planets, or WASP ⁘ an international collaboration of academic institutions that together operate two robotic observatories, one in the northern hemisphere and the other in the south. Each observatory uses an array of wide-angle cameras to measure the brightness of thousands of individual stars across the entire sky.