“The challenge with super-puff planets is that they don’t fit neatly into our models.”A super-puff planet almost shouldn’t exist.
A gas giant’s core typically has a mass at least 10 times the mass of Earth.
The first potential super-puff planets were identified in 2014, three of them orbiting a star called Kepler-51.
That was the first time scientists had come across planets with astonishingly low densities, and they didn’t know what to make of them.
“Do we have to scratch everything we understand about planet formation and start over?”
The discovery of these two gas giants, which are less dense than cotton candy, will help astrophysicists better understand the most extreme and unusual ways planets can form.
“We want to understand the full story of planet formation and evolution,” said George Dransfield, an astrophysicist at Oxford University who led the study. “The challenge with super-puff planets is that they don’t fit neatly into our models.”
A super-puff planet almost shouldn’t exist. It’s effectively a gas giant with an impossibly tiny core, one that should be too small to gravitationally pull in the vast volume of gases that scientists have found in their atmospheres.
A gas giant’s core typically has a mass at least 10 times the mass of Earth. But many super-puffs have total masses the core and atmosphere together that are less than that. “So how does a core one or two or five Earth masses accrete this large amount of gas?” said Jessica Libby-Roberts, an astronomer at the University of Tampa who was not involved in the study.
It makes little physical sense, and it’s a puzzle scientists have been working on for about a decade. The first potential super-puff planets were identified in 2014, three of them orbiting a star called Kepler-51. That was the first time scientists had come across planets with astonishingly low densities, and they didn’t know what to make of them.
“It just seemed impossible,” Libby-Roberts said. “Do we have to scratch everything we understand about planet formation and start over?”
