The Milky Way's Spiral Arms and Bar Authors: S. J. Carey, et al. (for the Spitzer Space Telescope team) PDF Link: Search "GLIMPSE survey Milky Way structure PDF" – the Publications of the Astronomical Society of the Pacific has an open-access paper on this.
However, the Galaxy’s current form is temporary. Observations from the Hubble Space Telescope have confirmed that the Milky Way is on an inescapable collision course with the Andromeda Galaxy . In roughly 4 billion years, these two spiral giants will merge to form a massive elliptical galaxy. 4. The Edge of Discovery galactic astronomy pdf
The most current research and advanced review articles are found here. While not a textbook, many senior researchers upload comprehensive lecture notes. The Milky Way's Spiral Arms and Bar Authors: S
The flat region containing most of a galaxy's gas, dust, and younger stars. This is where active star formation primarily occurs. (for the Spitzer Space Telescope team) PDF Link:
Search: Swinburne COSMOS Milky Way structure PDF → Excellent for beginners with diagrams.
: The Milky Way’s extended halo is composed of the remains of tidally shredded dwarf galaxies and globular clusters consumed over billions of years.