Hardy Planet

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Hardy Planet

A giant planet that’s orbiting a dead star is tough. It survived the star’s demise — a process that sent big blobs of hot gas flying out into space. And it’ll probably survive being eroded away by the star’s hot corpse.

The planet orbits a white dwarf — the remnant of a once “normal” star. As the star died, it expelled its outer layers into space, leaving only its hot core. The core is more than half as massive as the Sun, but only about one percent as wide — about the size of Earth.

Astronomers in Europe discovered a disk of gas and dust around the white dwarf. From the size and composition of the disk, they concluded that it’s being fed by a planet. It’s the first planet known to orbit a white dwarf.

The planet is several times the size of the white dwarf. That makes it about as big as Uranus or Neptune, two of the giants of our own solar system. But radiation from the white dwarf is blasting away the planet’s outer layers — at 3,000 tons per second. Much of the debris spirals toward the star, forming the disk.

The researchers say the planet should survive the stellar blowtorch, though. It’ll lose only a small fraction of its mass. It will continue to orbit the dead star as it slowly cools and fades into the long cosmic night.

The system is about 2,000 light-years away. It’s in Cancer, the crab, which is high overhead as night falls. It’s far too faint, though, to see without a telescope.

We’ll talk about a hot moon tomorrow.

Script by Damond Benningfield

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