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Birth and Death

June 13, 2016

Astronomers are watching acts of birth and death in the stars: the possible birth of an Earth-sized planet in one system, and the destruction of a dwarf planet in another.

The act of creation is taking place in a system known as TW Hydra. The star itself is a little smaller and a good bit fainter than the Sun. And it’s just 10 million years old, compared to four-and-a-half billion years for the Sun.

A disk of gas and dust encircles the star. And an array of radio telescopes in Chile found several gaps in the disk. The gaps may have been swept clean by newly forming planets. One of the gaps is about the same distance from TW Hydra as Earth is from the Sun. So a rocky planet may be taking shape there — a planet as massive as Earth or heavier.

A much smaller planet in another system appears to be at the opposite end of the planetary lifecycle: It’s being torn apart.

The object appears to be about as big as Ceres, the largest member of the asteroid belt. It orbits a white dwarf — the small, dead core of a once-normal star.

Astronomers studied the system a couple of times last year. The first time, they saw the dwarf planet cross in front of the white dwarf. The second time, they saw evidence of several smaller chunks of material, with a cloud of debris around them. That suggests that the gravity of the white dwarf pulled the small planet apart. Eventually, the pieces may fall into the white dwarf — ending the life of a tiny planet.

Script by Damond Benningfield

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