In 2003, astronomers confirmed this core to be a
specific type of central region known as an HII nucleus — a name that indicates the presence
of ionized hydrogen — that is likely to be creating many hot new
stars.
We conclude that this class
of semi-empirical models successfully grasp the main trends
of the rotational behaviour
of solar -
type stars as they evolve and make
specific predictions that may serve as a guide for further development.