Scientists observe colliding stellar winds from two colossal stars.
A star cluster located about 4,700 light-years away in the constellation Cygnus holds some of the galaxy’s rarest suns. Of some 3,000 stars in the group, about 100 are classified as type O. These massive suns shine so hot and bright they drive their own surface gases outward at high speed in powerful outflows called stellar winds. Two of these stars circle each other tightly, forming the binary system known as Cygnus OB2 #9. Scientists long suspected that the winds from these stars collided, but never had direct evidence of this interaction. In June 2011, scientists made a breakthrough discovery. Using NASA’s Swift satellite and other space telescopes, they observed a sharp rise in X-rays coming from the system as the stars raced toward their closest approach. It turns out the X-ray increase was tied to their colliding winds, crashing together at speeds of millions of miles per hour. Watch the video to learn more.