Ira Sprague Bowen

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Ira Sprague Bowen

There was something odd about the Cat’s Eye Nebula — a colorful bubble of gas blown by a dying star. Parts of the nebula have a greenish color. For decades, astronomers thought that glow was produced by a new chemical element. They called it nebulium.

An astronomer born 125 years ago today proved otherwise. Ira Sprague Bowen found that the green glow is produced not by a new element, but by a never-before-seen form of a common element: oxygen. The oxygen is “doubly ionized” — radiation from the star zaps the atoms, stripping away two of their electrons. Since Bowen’s discovery, it’s been found in the remains of many other dying stars.

Bowen specialized in studying the chemical elements — first in the lab, and later, in the stars and their remnants. He started his work at the University of Chicago, then continued at Caltech. He became director of the university’s Mount Wilson Observatory, and the first director of its new Palomar Observatory. He held the posts until he retired, in 1964. He died in 1973, at age 74.

The Cat’s Eye Nebula is several thousand light-years away, in Draco, the dragon. The nebula is in the north-northwest at nightfall. It continues to expand, as the dying star dumps 20 trillion tons of gas into space every second. That includes oxygen atoms that the star will then zap — creating the green glow once thought of as a new chemical element.

Script by Damond Benningfield

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