Carina–Sagittarius Arm
In 2008, infrared observations with the Spitzer Space Telescope showed that the Carina–Sagittarius Arm has a relative paucity of young stars, in contrast with the Scutum-Centaurus Arm and Perseus Arm. This suggests that the Carina–Sagittarius Arm is a minor arm, along with the Norma Arm (Outer Arm). These two appear to be mostly concentrations of gas, sparsely sprinkled with pockets of newly formed stars. A number of Messier objects and other objects visible through an amateur's telescope or binoculars are found in the Sagittarius Arm (here listed approximately in order from east to west along the arm):
Minor arm
The Carina–Sagittarius Arm is one of the most pronounced arms in our galaxy as many HII regions, young stars and giant molecular clouds are concentrated in it. Beyond the dissipated zone it is the Carina Arm.