Are all Stars part of a Galaxy?
Stars can’t form outside of a galaxy, there is no gas there and nothing to compress the gas even if it was there. However, some stars are outside the disk of the galaxy. They’re in an area normally called the halo of the galaxy. But they are gravitationally bound to it. For info on this area around our galaxy, see: http://en.wikipedia.org/wiki/Galactic_ha… However, that said, it is possible, but pretty rare, for a star to be ejected from a galaxy. Astronomers located a star, SDSS J090745.0+24507 (great name, huh?), that is travelling at such a speed that is moving faster than our galaxy’s escape velocity and will eventually leave the Milky Way. It was probably part of a binary star system that was gravitationally distrubed by a black hole. So, it’ll eventually be an intergalactic star. See: http://en.wikipedia.org/wiki/SDSS_J09074… Any
