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Zeta Puppis

April 7, 2019

The brightest star of the constellation Puppis, which represents the stern of the ship Argo, is one in a million — or one in several million, to be more precise. It’s a member of the hottest and heaviest class of stars, known as Class O. This class is also the rarest of all — there are no more than a few tens of thousands of members in the entire galaxy.

Zeta Puppis is low in the south as night falls this evening. It’s far to the lower left of Sirius, the brightest star in the night sky.

Zeta Pup looks only a fraction as bright as Sirius, but that’s only because of their distances. Sirius is less than nine light-years away, but Zeta Pup is more than a hundred times farther. So if you put the two stars side by side, Zeta Puppis would shine thousands of times brighter.

Class O stars are the most massive “main-sequence” stars — stars that are in the prime of life. They’re many times heavier than the Sun. Such stars are squeezed more tightly by gravity, heating their cores to billions of degrees. That also heats their surfaces, making them much hotter and bluer than the Sun.

The heat in an O star’s core cranks up the rate of nuclear reactions. So even though Zeta Puppis is more massive than the Sun, it’ll live a much shorter life — only about a million years, versus 10 billion years for the Sun. And at the end, it’s likely to blow itself to bits as a supernova — a brilliant demise for a brilliant star.

Script by Damond Benningfield

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