Thanks. Now the question is, how big are
R and r?
R might be the distance from Galactic Center that heavy elements start becoming too scarce to make a planet similar to ours. I don't know if that would coincide with the distribution of Population I stars or not.
r would have to be the distance from the Center that radiation stops being too high for us without wearing suits. I don't have a clue what this figure is, or which edge of the torus we lie more toward.
I wonder if anyone's ever created a map showing a "Galactic Habitable Zone" (like the "habitable zone" where liquid water can exist in our own solar system).
