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Six Stars, One System

Animation shows six stars, all part of a single system called TYC 7037-89-1
Richard Barkus, NASA-JPL/Caltech

Two-star systems are quite common in our galaxy. Even systems with three stars are not especially rare – our nearest stellar neighbor, Alpha Centauri, is just such a trio. 

But we enter much more rarified territory if we look some 1,900 light-years away to find TYC 7037-89-1. It’s a system of six stars, all gravitationally bound to one another. From Earth’s vantage point, one other quality allows this system to notch an observational first: Each of its three pairs of stars cross the faces of their companions. In other words, all three can put on a dazzling show for astronomers of frequent and multiple eclipses. 

The details of this binary star ballet are worth noting. For two of the pairs, the time it takes for their companion stars to orbit each other is about the same: 1.5 days. These two pairs also form a third gravitational relationship, locked in their own mutual orbit of four years. 

And what about that third pair? These two stars also orbit each other, in this case every eight years, and together they trace yet another, wider orbit around the other two pairs. The orbit is wide indeed. It takes 2,000 years to complete. 

How can six stars wind up in such an intricate gravitational dance? The formation history of this system is unknown, but one possible explanation is that they were all born together, in a single (and very active) star-forming region. While the offspring of such stellar nurseries typically disperse, these possible siblings might have stayed together, maintaining their gravitational relationships even as they matured. 

‘Other Stars, Other Worlds’ — other stories

A retro looking travel poster for the exoplanet Kepler-16b shows a human standing on a rocky world with two suns large in the foreground. There is a larger white-yellowish sun, with a smaller orang sun. The person, seen from behind, has two criss-crossing shadows between an outcropping of rocks, reminiscent of the American Southwest. Like Luke Skywalker's planet "Tatooine" in Star Wars, Kepler-16b orbits a pair of stars. Kepler-16b is a gas giant, like Saturn, so it would have no solid surface to stand on. The view here is of and from an imagined nearby moon. Prospects for life on this unusual world aren't good, as it has a temperature similar to that of dry ice.

Learn about Kepler-16 b and the twin suns in its sky.

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The TRAPPIST-1 star and its clutch of rocky planets — are any capable of life?

Kepler-90

A Sun-like star surrounded by eight planets — just like us! But look again...

infographic showing the configuration of a Sextuple System

Six stars, paired up, twirling around and between each other.