What type of galaxy is characterized by a regular structure and ongoing star formation?

A spiral galaxy is characterized by its distinct structure that includes a central bulge surrounded by a flat, rotating disk that often contains spiral arms. These arms are sites of ongoing star formation, which occur because the dense regions within the arms can collapse under their own gravity to create new stars.

The presence of these spiral arms, as well as the bright and active star-forming regions they harbor, are distinguishing features of spiral galaxies. Not only do these galaxies demonstrate a regular structure, but they also show a mix of young, blue stars and older, red stars, further signifying that star formation is an ongoing process. The combination of these features makes spiral galaxies unique compared to other types, such as elliptical galaxies, which do not exhibit significant star formation, or irregular galaxies, which lack a defined shape and structure.