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Contact Binaries III

August 17, 2012

A star system that offers plenty of variety is in the west on August evenings. It’s above yellow-orange Arcturus, one of the brightest stars in the night sky. 44 Bootis is pretty faint, though, so you need dark skies to see it, and a good sky chart wouldn’t hurt.

A good backyard telescope shows two stars, not one. The brighter of the two is quite similar to the Sun — about the same size, color, brightness, and mass.

What no telescope can show you is that the other star is in fact two stars on its own. One of them is a little smaller and fainter than the Sun, while the other is smaller still.

Even though 44 Bootis is only about 40 light-years away, not even big research telescopes can separate the two stars. That’s because they aren’t actually separate — they touch each other. In fact, they share the gas in their outer layers, with the gas circulating around the cores of both stars. The two cores are separated by just three-quarters of a million miles — three times the distance from Earth to the Moon — so they whirl around each other about four times a day.

And recent observations suggest there’s yet another component in the 44 Bootis system — a brown dwarf. The object hasn’t been confirmed, but if it exists it’s probably a few dozen times the mass of Jupiter, the solar system’s largest planet. That would put it just below the cutoff line for true stars — adding to the variety of this odd little star system.

Script by Damond Benningfield, Copyright 2012


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