Its an empty vacuum, There is nothing there. Literally nothing.
solar system
in the halo
It has been estimated that there are between 200 -> 400 billion stars in the Milky Way Galaxy
between 200 and 400 billion stars
Most new, young, stars can be found in the arms of spiral galaxies
Large stars are distributed all over our galaxy, there is no single location for them.
A galaxy is by a definition a group of stars. If there were no stars it could not be a galaxy.
A dwarf galaxy might contain this number of stars. A galaxy will contain billions of stars.
Every galaxy contains stars, if that's what you mean. "Galaxy" means "big bunch of stars". No stars ===> no galaxy.
A typical galaxy may have anywhere between a few million (106) stars, and over a trillion (1012) stars. Our own Milky Way is estimated to have between 200 and 400 billion (2x1011-4x1011) stars.
The sun is one of an estimated 400 billion stars in our galaxy.
Hydrogen and helium.