Binary stars are very common, and about half of all stars have such a celestial companion. Moreover, several exoplanets have now been found in binary star systems. So the formation of these stars touches on many astronomical topics.
Bo described how magnetic fields can control the orbital evolution of binary stars and influence the accretion of mass by the stars. For example, magnetic fields can sculpt the shape of accretion disks around the stars into complex shapes, filaments and strands (as shown at left).
Since these accretion disks mass onto the young stars, understanding their shapes, dynamical evolution, and the effects of magnetic fields on both these are important for understanding the population of binary stars we can see.