Stars are known to form near the spiral arms of our galaxy, the Milky Way galaxy, in large clouds of gas known as Giant Molecular Clouds (GMCs). An example of a GMC is contained in the Orion Constellation, the Orion Giant Molecular Cloud. The Orion GMC is a stellar nursery. The Orion GMC is actually a complex of hierarchially clustered structures (for more, see also). Stars are thought to form from the densest clumps of the cloud. The problem is that the star forming clumps contain large amounts of angular momentum; normal stars like the Sun are essentially nonrotating and so contain very little angular momentum when compared to the star forming clumps. So, the question is " Where did all of the angular momentum go?"
We can store the angular momentum (the measure of the spin motion about an axis) in at least two ways: the rotation of the objects or in the orbital motion of the objects. For example, in the Solar System, the Sun contains only ~1-2 % of the angular momentum in its spin; most of the angular momentum is carried by the planets such as Jupiter and Saturn in their orbital motions. The analogous situation arises for stars in that the spins of stars account for very little of the angular momentum, most of the angular momentum is stored in the orbital motions of stars (binary star systems, for example).
The natural solution to the angular momentum problem is thus that multiple star systems and perhaps planetary systems are the norm and not the exception.
