A channel connecting two spiral arms.
Scientists in Germany, France and the United Kingdom recently surveyed the distribution of carbon monoxide gas in the Milky Way by accident, with a narrow sine wavy gas fiber straddling the axis boom and a smaller "3 kilosec" boom.
This gas fiber is about 17,000 light-years away from the center of the Milky Way, about 7,000 to 13,000 light-years long, and has a total mass equivalent to about 9 suns. Although such gas fibers have been found in the Milky Way in the past, they are parallel to the spiral arm. This fiber is different in that it extends outward from the side close to the silver core, connecting the two spiral arms together.
Many extragalactic galaxies have such fibers. These "barbed" fibers are figuratively referred to by scientists as the "feathers" of galaxies. But from Earth's point of view, humans don't see the full picture of the Milky Way. Therefore, although scientists have always suspected that the Milky Way also has such "feathers", it is the first time that "feathers" have been really discovered.
Scientists named the "feather" the "Gangotri wave." "Gangotry" is the name of the glacier at the head of the Ganges. Indians call the Milky Way the "Akasha Ganga." It is called a "wave" because the gas fiber is not as straight as scientists expected, but is a zigzag sine wave.
Scientists say it's not yet possible to explain why the gas fiber is so tortuous. The only thing that is certain is that it must have been influenced by some unknown force.
reference
A Kiloparsec-scale Molecular Wave in the Inner Galaxy: Feather of the Milky Way?
http://dx.doi.org/10.3847/2041-8213/ac341f