New Star Found in Big Dipper

A new star was discovered in the Big Dipper! One of the stars that makes the bend in the ladle's handle, Alcor, has a smaller red dwarf companion, new observations have revealed. Alcor and its cousins in the Big Dipper formed from the same cloud of matter about 500 million years ago, something unusual for a constellation since most of these patterns in the sky are composed of unrelated stars. In March, a group of astronomers attached a coronograph and adaptive optics to the 200-inch Hale Telescope at the Palomar Observatory in California and pointed it to Alcor. (Adaptive optics counteract interference from Earth's atmosphere by making swift, real-time changes in the shape of a telescope's mirror during observations.)

"Right away I spotted a faint point of light next to the star," said Neil Zimmerman, a graduate student who is working on his Ph.D. with the American Museum of Natural History in New York. "No one had reported this object before, and it was very close to Alcor, so we realized it was probably an unknown companion star."

When the scientists looked back at the star at a later time, to see if the star had any unusual patterns.

"We went back 103 days later and found the companion had the same motion as Alcor," said Ben R. Oppenheimer, Curator and Professor in the Department of Astrophysics at AMNH.

Alcor and its newly found, smaller companion, Alcor B, are both about 80 light-years away from Earth and orbit each other every 90 years or more. Scientists have deducted that the star is a "red dwarf" that is roughly 250 times the mass of Jupiter, or roughly a quarter of the mass of our Sun.

http://www.usatoday.com/tech/science/space/2009-12-10-bigdipper10_ST_N.htm