Carina–Sagittarius Arm

A study was done with the measured parallaxes and motions of 10 regions in the Sagittarius arm where massive stars are formed. Data was gathered using the BeSSeL Survey with the VLBA, and the results were synthesized to discover the physical properties of these sections (called the Galactocentric azimuth, around −2 and 65 degrees). The results were that the spiral pitch angle of the arms is 7.3 ± 1.5 degrees, and the half-width of the arms of the Milky Way were found to be 0.2 kpc. The nearest part to the Sun is around 1.4 ± 0.2 kpc away. ==Minor 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. ==Visible objects==

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): • M11, the Wild Duck Cluster in Scutum (RA 18h 51m) • Open Cluster M26 in Scutum (RA 18h 45m) • M16, the Eagle Nebula in Serpens (RA 18h 19m) • M17, the Omega Nebula in Sagittarius (RA 18h 20.4m) • Open Cluster M18 in Sagittarius (RA 18h 19.9m) • Globular Cluster M55 in Sagittarius (RA 19h 40m) • M24, the Small Sagittarius Star Cloud (RA 18h 17m) • Open Cluster M21 in Sagittarius (RA 18h 5m) • M8, the Lagoon Nebula in Sagittarius (RA 18h 4m) • NGC 3372, the Carina Nebula in Carina (RA 10h 45m) ==See also==