We observe them as pulsars. Red Giant stars swell up to 500 times the diameter of the Sun. Betelguese, Antares and Aldebaran are well known red giant stars. This is 100 million times the diameter of Pluto's orbit. Stars and dust clouds towards the center of the Milky Way.
Stars form half the detectable mass of the Milky Way.
The other half is in the form of gas and dust. The nearest large spiral galaxy like the Milky Way is the Andromeda galaxy, about 2.7 million light years away. 3,734 accesses .