Bizarre ‘Cotton-Candy' Planet Is Changing Our Sense of What’s Possible - Gizmodo

Benneke and Piaulet just completed a four-year survey of WASP-107b, a gas giant with a mass in the Neptune range but a radius the size of Jupiter’s.

This world is very close to its host star, so a year on WASP-107b lasts just 5.7 days.

To do so, the team measured the degree to which the exoplanet caused its host star to wobble—a technique astronomers refer to as the radial velocity method.

What’s more, 85% of the planet’s entire mass is packed into the thick layer of gas immediately surrounding the solid core, according to the paper.

In other words, the core of WASP-107b doesn’t appear to have sufficient mass, and thus gravitational influence, to facilitate the formation of a gas giant inside the protoplanetary disk—the gigantic disk of dust and gas that encircles a star during the planet formation process.

Current models of gas giant formation are biased towards the formation of Jupiter- and Saturn-like objects, and they suggest embryonic cores need to be at least 10 times heavier than Earth.

Any lighter, and the core is unable to gather, or accrete, sufficient amounts of gas and dust prior to the dissipation of the protoplanetary disk.

“For WASP-107b, the most plausible scenario is that the planet formed far away from the star, where the gas in the disc is cold enough that gas accretion can occur very quickly,” said Piaulet in the statement.

WASP-107c has approximately one-third the mass of Jupiter, so it’s considerably heavier than its companion, WASP-107b?