New Star Found in Big Dipper

Thursday, December 10 11:40 am

The Big Dipper has just gotten richer by one star. A new image from Ben Oppenheimer’s Project 1640 team shows that Alcor, one of the stars that makes the bend in the ladle’s handle, has a companion. Now named Alcor B, the new star is a faint, smaller red dwarf. It was discovered using Project 1640’s coronograph which blocks out the main star’s light to see faint objects nearby.

But Oppenheimer and his team, including graduate student Neil Zimmerman who was first author of the scientific paper, have done more than find a new star. After re-observing the star some 100 days later, they were able to show that the two stars orbit each other using an innovative technique called “common parallactic motion.”

“We used a brand new technique for determining that an object orbits a nearby star, a technique that’s a nice nod to Galileo,” says Oppenheimer. Galileo tried to use “common parallactic motion” to show that the Earth orbited the Sun, but his equipment was unfortunately not precise enough. The idea is that nearby stars move in an annual, repeatable motion simply because the observer is on Earth and Earth is circling the Sun.

Project 1640 used the idea to show that both stars, Alcor A and B, move together.