About 212 light-years from Earth, a gas giant light enough to be nicknamed the “super-puff” or “cotton candy” planet orbits extremely close to its host star. The exoplanet is so light that astronomers question everything we previously knew about how gas giants form.
This super-puff pastry exoplanetknown as WASP-107b, is about the size of Jupiter, but only about one-tenth the mass – or about 30 times the mass of Earth. Nuclear mass is significantly smaller than astronomers thought it needed to create a gas giant planet like Jupiter and Saturn, according to a new study published Monday in The Astronomical Journal.
The discovery made by Ph.D. student Caroline Piaulet, led by Professor Björn Benneke at the University of Montreal, indicates that gas giants form much more easily than previously thought.
“This study pushes the boundaries of our theoretical understanding of how gigantic planets are formed. WASP-107b is one of the most inflated planets out there, and we need a creative solution to explain how these tiny cores can create such massive gas envelopes. building, ”said co-author Eve Lee in a statement.
WASP-107b is not an entirely new discovery – astronomers first discovered it in the constellation Virgo in 2017. The planet is very close to its star, more than 16 times closer to the sun than Earth, and completes every 5.7 days a job.
WASP-107b is one of the least dense exoplanets scientists have ever found. They nicknamed similar types of planets – gas giants with the density of cotton candy – supersclouds.
ESA / HUBBLE, NASA, M. KORNMESSER
To find the planet’s surprising mass, astronomers studied observations from the Keck Observatory in Hawaii. They used a technique called the radial velocity method, which studies the wobbling motion of a planet’s star caused by a planet’s gravity, to calculate its mass.
Scientists were shocked to conclude that the solid core of WASP-107b has a mass no more than four times that of Earth, meaning that more than 85% of its mass comes from the thick gaseous layer around the core. This is a dramatically different breakdown than Neptune, which has a similar mass but keeps only 5% to 15% of it in its gas layer.
Based on their knowledge of Jupiter and Saturn, scientists previously believed that a solid core at least 10 times the mass of Earth would be needed to obtain enough gas to form a gas giant planet. WASP-107b challenges that theory.
“This work addresses the fundamentals of how giant planets can form and grow,” said Benneke. “It provides concrete evidence that massive gas envelope growth can be activated for nuclei that are much less massive than previously thought.”
Lee states that: “The most likely scenario is that the planet originated far away from the star, where the gas in the disk is cold enough for gas accretion to take place very quickly. The planet could later migrate to its present position, either by interactions with the disk or with other planets in the system. “
While studying the planet, the team came across another in the same system, WASP-107c. It has a mass about one-third that of Jupiter, and takes three years to orbit its host star once.
The planet’s oval orbit suggests that the astronomers’ new hypothesis is on the right track.
“WASP-107c, in some ways, has preserved the memory of what happened in its system,” said Piaulet. “Its great eccentricity indicates a rather chaotic past, with interactions between the planets that could have resulted in significant displacements, as was suspected for WASP-107b.”
The team hopes to continue studying the strange planet with the launch of the James Webb space telescope this year.