High Quality Content by WIKIPEDIA articles! The Carina-Sagittarius Arm (also known as Sagittarius Arm or Sagittarius-Carina Arm, labeled -I) is generally thought to be a minor spiral arm of our home galaxy, the Milky Way. Each spiral arm is a long, diffuse curving streamer of stars that radiates out from the galactic center. These gigantic structures are often composed of billions of stars and thousands of gas clouds. The Carina-Sagittarius Arm is one of the most pronounced arms in our galaxy as a large number of HII regions, young stars and giant molecular clouds are concentrated in it.