Do all the stars in the twelve constellations belong to the Milky Way?

Not the Milky Way, but the star system where the solar system is located, including120 billion stars and a large number of star clusters and nebulae, as well as various types of interstellar gas and interstellar dust. Its diameter is about 100000 light years, its center thickness is about 12000 light years, and its total mass is140 billion times that of the sun. The Milky Way is a spiral galaxy,

This is a galaxy, and you can tell the difference from its name. The friend upstairs extracted the information, and although there were some minor flaws, it also hit the nail on the head. The Milky Way is made up of hundreds of billions of stars, but there are only one million clusters. I dare not take away the beauty of others, so I won't go into details on this question.