New Ultradense Planet Found; Astronomers Baffled
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Dubbed CoRoT-20b, the planet is thought to be a gas giant about four-fifths the size of Jupiter and orbits close to a sunlike star.
Despite the new planet's relatively diminutive size, this world has four times Jupiter's mass, making CoRoT-20b one of the densest known planets, a new study says.
That poses a problem for astronomers: If CoRoT-20b is structured like a traditional gas giant, with a solid core surrounded by a gassy atmosphere, the planet's core would have to make up 50 to 77 percent of the world's total mass.
By contrast, Jupiter's core is thought to represent just 15 percent of that planet's mass.
To have such a robust core, CoRoT-20b would defy current theories for how planets form.
Astronomers think planets are born from disks of debris that surround newborn stars. In our solar system, the sun's so-called protoplanetary disk gave rise to several worlds and still had leftovers from planet formation—what we callasteroids and comets.
However, the new study says that CoRoT-20b would have had to have sucked up every last atom of material heavier than helium from its star's protoplanetary disk to form the planet's massive core.
"That is something difficult to understand, and to admit," said study leader Magali Deleuil, of the Laboratory of Astrophysics of Marseilles in France.
