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September 23, 2015

Thinking about the orbital motions of the star system known as Dabih is enough to make you dizzy. It consists of at least five stars, all orbiting each other in various configurations. In fact, one pair of stars has three different orbital motions.

Dabih — from an Arabic phrase that means “the butcher” — is one of the leading lights of Capricornus. It’s close above or to the upper right of the Moon at nightfall — less than the width of a finger held at arm’s length. It’s not all that bright, though, so it may be tough to see through the lunar glare.

Binoculars reveal that the system consists of two stars, known as Dabih Major and Dabih Minor. And it turns out that each of those stars is a group of two or more stars on its own.

The two groups are separated by about a third of a light-year. At that range, it takes perhaps a million years for the groups to complete a single orbit around each other.

What’s more, the stars within the groups are orbiting each other as well. Dabih Major, for example, consists of at least two stars — one that’s much bigger and brighter than the Sun, and one that’s a little less impressive but still a stunner. The two stars orbit each other once every four years.

Dabih Minor consists of at least three stars. Two of them form a tight pair. These stars orbit each other, but they also orbit the third member of the system. And the entire trio pursues a mutual orbit with Dabih Major — a series of loops that’s enough to make you dizzy.


Script by Damond Benningfield, Copyright 2015

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