“Super puff” exoplanet is as big as Jupiter but 10 times lighter, confusing astronomers

About 212 gentle years from Earth, a fuel big gentle sufficient to be nicknamed a “super-puff” or “cotton sweet” planet is circling extraordinarily near its host star. The exoplanet is so gentle, it is left astronomers questioning the whole lot we beforehand knew about how fuel giants type.

This super-puff exoplanet, referred to as WASP-107b, is about the identical dimension as Jupiter, however solely about one-tenth the mass — or about 30 instances extra large than Earth. Based on a brand new research printed Monday in The Astronomical Journal, its core mass is considerably smaller than astronomers thought mandatory for the creation of a fuel big planet like Jupiter and Saturn.

The invention, made by Ph.D. scholar Caroline Piaulet beneath the supervision of professor Björn Benneke on the College of Montreal, signifies that fuel giants type way more simply than beforehand believed.

“This research pushes the boundaries of our theoretical understanding of how giant-sized planets type. WASP-107b is without doubt one of the puffiest planets on the market, and we’d like a artistic answer to elucidate how these tiny cores can construct such large fuel envelopes,” coauthor Eve Lee mentioned in a press release.

WASP-107b is not a model new discovery — astronomers first detected it within the Virgo constellation in 2017. The planet could be very near its star, over 16 instances nearer than Earth is to the solar, finishing one orbit each 5.7 days.

WASP-107b is without doubt one of the least dense exoplanets scientists have ever discovered. They’ve nicknamed related kinds of planets — fuel giants with the density of cotton sweet — super-puffs.

To search out the planet’s shocking mass, astronomers studied observations obtained on the Keck Observatory in Hawaii. They used a method known as the radial velocity technique, which research the wobbling movement of a planet’s star brought on by a planet’s gravitational pull, with a view to calculate the mass.

Scientists had been shocked to conclude that the strong core of WASP-107b has a mass that’s not more than 4 instances that of the Earth, which means greater than 85% of its mass stems from the thick gaseous layer surrounding the core. It is a dramatically completely different breakdown from Neptune, which has the same mass however holds simply 5% to fifteen% of it inside its fuel layer.

Primarily based on their data of Jupiter and Saturn, scientists beforehand believed {that a} strong core a minimum of 10 instances the mass of Earth can be wanted to amass sufficient fuel for a fuel big planet to type. WASP-107b challenges that idea.

“This work addresses the very foundations of how big planets can type and develop,” Benneke mentioned. “It gives concrete proof that large accretion of a fuel envelope will be triggered for cores which are a lot much less large than beforehand thought.”

Lee posits that, “Essentially the most believable state of affairs is that the planet shaped distant from the star, the place the fuel within the disc is chilly sufficient that fuel accretion can happen in a short time. The planet was later capable of migrate to its present place, both by interactions with the disc or with different planets within the system.”

Whereas finding out the planet, the group stumbled upon one other in the identical system, WASP-107c. It has a mass that’s about one-third that of Jupiter and takes three years to orbit its host star as soon as.

The planet’s oval-shaped orbit means that the astronomers’ new speculation is heading in the right direction.

“WASP-107c has, in some respects, stored the reminiscence of what occurred in its system,” mentioned Piaulet. “Its nice eccentricity hints at a relatively chaotic previous, with interactions between the planets which may have led to important displacements, just like the one suspected for WASP-107b.”

The group hopes to proceed finding out the unusual planet with the launch of the James Webb Area Telescope this 12 months.

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