I have a few questions. Would a given galaxy contain same amount of stars and gas through its lifetime? I want to say no, but I was thinking for every dead star, there will be a new star forming, and the gases would be preserved in the galaxy. And would the spiral disk component of the Milky Way contain all of the stars in its galaxy? I was wondering if this disk covers the diameter of the Milky Way. Lastly, do newly formed stars usually have disks? Thank you!