What is the name of the elongated central structure of the Milky Way?

The elongated central structure of the Milky Way is called the Galactic bar. It is a large, bar-shaped concentration of stars crossing the Galaxy’s central region, with the central bulge and Sagittarius A* located within that broader area.

The Milky Way is therefore classified as a barred spiral galaxy rather than simply a spiral galaxy. The bar influences the orbits of stars and gas, and it helps channel gas inward through gravitational resonances. That inward flow can supply material for star formation near the Galactic Center.

Astronomers began seriously proposing the Milky Way’s barred structure in the 1960s. Infrared observations were especially important because clouds of dust obscure the Galaxy’s center in visible light. Spitzer Space Telescope observations released in 2005 provided strong confirmation that the central structure was larger than earlier estimates suggested.

The Galactic bar should not be confused with a spiral arm, which extends outward through the disk, or the central bulge, which is a denser, roughly spheroidal or boxy-peanut-shaped stellar region. The bar is the elongated stellar structure that helps shape the Galaxy’s inner architecture.