Super-Earths, meet superpuffs, a lighter weight class of planet | Science News

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Super-Earths, meet superpuffs, a lighter weight class of planet

Underweight, oversized planets formed in outskirts of star systems

By
2:17pm, November 30, 2015
a superpuff planet

BIG PERSONALITY  Superpuffs (one illustrated) are extra fluffy planets that formed far from their star and subsequently wandered in closer, a new study suggests.

Superpuff
\SOO-per-puf\ n.

A gassy planet, close to its star, with a puzzlingly small mass.

Not to be confused with a generic breakfast cereal, superpuffs are fluffy planets snuggled up to their suns. A superpuff develops its inflated persona by forming far from its star and then wandering inward, astronomers Eve Lee and Eugene Chiang of the University of California, Berkeley suggest online November 1 at arXiv.org. Starting out in the outskirts of a fledgling planetary system, the researchers say, would mean more cold gas is available to stick to a rocky core.

Superpuffs are quite large for their mass. They typically weigh a few times as much as Earth but stretch up to 10 times as wide. That’s about as large as Jupiter but roughly one one-hundredth of its mass. These puffy worlds are the opposite of the rocky heavyweights known as super-Earths (

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