A Quartet of Stars, Locked in a Tight Embrace

Astronomers think that many star systems actually contain multiple stars. There are doubles, triples and even quadruple groupings of stars locked together in a gravitational embrace. Astronomers recently discovered a system with 4 stars orbiting within the orbit of Jupiter. It’s a surprising discovery considering no telescope on Earth is powerful enough to separate them into distinct points of light.

The star system, located 166 light-years from here, is called BC 22 5866, and its discovery was announced the Winter meeting of the American Astronomical Society in Austin. An international team of astronomers described how they had been monitoring several hundred star systems when they saw something unusual.

They were analyzing the light from one of hundreds of stars when they realized that its light could be broken into 4 separate stars. Even the most powerful telescopes on Earth can’t actually resolve the stars into separate objects, and that means they’re close together… really close.

The stars are paired up together into binary groupings, and then these two pairs orbit a common centre of gravity. One pair orbits each other in less than 5 days – at a distance of a mere 0.06 astronomical units (1 AU is the distance from the Earth to the Sun). The second pair takes 55 days to complete an orbit, at a distance of 0.26 AU.

And finally, the two pairs take about 9 years to orbit one another at a distance of 5.8 AU – within the orbit of Jupiter in our own Solar System.

It must have been a very special system to allow 4 individual stars to form this closely together.

“The extraordinarily tight configuration of this stellar system tells us that there may have been a single gaseous disk that forced them into such small orbits within the first 100,000 years of their evolution, as the stars could not have formed so close to one another. This is the first evidence of a disk completely encompassing four stars,” says Dr. Shkolnik of the University of Hawaii’s Institute for Astronomy. “It is remarkable how much a single stellar spectrum can tell us about both the present and the past of these stars.”

Original Source: IfA News Release