An ellipsoidal mass of stars and interstellar matter that occupies the central regions of a spiral galaxy. In our own Galaxy, it is some 30,000 light years across, and is occupied primarily by older orange and redstars. There is evidence to suggest that a massive black hole lies in its central regions, and indeed this may be a common feature of spiral galaxies in general.
NGC 6384 in Ophiuchus is a spiral galaxy showing a pronounced nuclear region. In this case, the nucleus is ellipsoid in form, representing an intermediate stage towards a barred spiral form. Imagery provided by Aladin sky atlas