Published March 12, 2010
Two extremely dense stars in an intimate dance are spinning around each other in just 5.4 minutes—making them the fastest known stellar partners in the galaxy, astronomers have confirmed.
To have such a speedy orbit, the stars must be moving at about 310 miles (500 kilometers) a second, the team calculates.
The whirling duo, known as HM Cancri, also has the tightest orbit of any known "binary" star system. (Related: "First Proof 'Tight' Double Suns Can Have Planets.")
Both stars are white dwarfs—the dense, white-hot remnants left behind when sunlike stars die. The stellar corpses are separated by no more than three times the width of Earth.
In such tight quarters, hot gases flow between the two stars, releasing huge amounts of energy."This is the most extreme example of one of these double white dwarf systems we have so far," said study co-author Danny Steeghs of the University of Warwick in the U.K.