'Gangotri wave' connecting two of Milky Way's spiral arms discovered

A team of researchers from Germany, France and the U.K. has discovered a long thin filament of dense gas connecting two of the Milky Way galaxy's spiral arms. In their paper published in The Astrophysical Journal Letters, the group describes their work studying carbon monoxide gas in the galaxy.

Figure 1. (Top) 13CO integrated intensity map from the SEDIGISM survey in the velocity range −95 to −75 km s−1 showing a wave-like feature. (Bottom) 12CO integrated intensity map from the ThrUMMS survey in the same velocity range as the top panel, smoothed to an angular resolution of 5'. Images are stretched along the y-axis for a better visualization.

In their work, the researchers were studying concentrations of carbon monoxide gas in data from the APEX telescope in San Pedro de Atacama, Chile. They noticed concentrations that had not been seen before, and after taking a closer look, discovered that it was part of a large gas formation that extended from near the center of the galaxy outward, connecting two of the arms that give the galaxy its distinctive look. https://phys.org/news/2021-11-gangotri-milky-spiral-arms.html