For the first time, scientists have been able to take a direct (X-Ray) picture of a binary star. The stellar pair (pictured using the Chandra telescope) is some 420 light years away from us. The distance between the stars (Mira A and B) is about twice the distance between Pluto and the Sun.
Mira A is a highly evolved red giant star. Mira B is a white dwarf. Mira A is losing gas rapidly from its upper atmosphere via a stellar wind. Mira B exerts a gravitational tug that creates a gaseous bridge between the two stars. Gas from the wind and bridge accumulates in an accretion disk around Mira B and collisions between rapidly moving particles in the disk produce X-rays.

Mira B (left) and A (Courtesy: Chandra)The ability to distinguish between the interacting stars allowed a team of scientists to observe an X-ray outburst from Mira A. An ultraviolet image made by the Hubble Space Telescope was key to identifying the X-ray outburst with the red giant star.
Mira A (or simply, Mira) was named "The Wonderful" star in the seventeenth century because its brightness was observed to wax and wane over a period of about 330 days. In this advanced red giant phase of Mira A's life, its diameter has swollen to about 600 times that of the Sun and it is pulsating, due to increasingly energetic nuclear reactions in its core.
X-ray studies of the Mira star system may also provide better understanding of interactions between other binary star systems consisting of a "normal" star and a collapsed star such as a white dwarf, black hole or a neutron star.