New Ultradense Planet Found; Astronomers Baffled

A newly discovered planet 4,000 light-years away is just too dense.
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.

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