A long, thin filament of cold, dense gas extends jauntily from the galactic center, connecting two of the galaxy’s spiral arms, astronomers report last month in the Astrophysical Journal Letters. This is the first time that such a structure, which looks like the barb of a feather fanning off the central quill, has been spotted in the Milky Way.
The team that discovered our galaxy’s feather named it the Gangotri wave, after the glacier that is the source of India’s longest river, the Ganges. Due to distinct wave-like shape and its peculiar orientation makes this cloud.
The filamentary cloud is at least 2.0 kpc in extent, considering the uncertainties in the kinematic distances, and it could be as long as 4 kpc. The vertical distribution of this highly elongated structure reveals a pattern similar to that of a sinusoidal wave. The exact mechanisms responsible for the origin of such a kiloparsec-scale filament and its wavy morphology remains unclear.
The Gangotri wave has another unusual feature: waviness. The filament appears to wobble up and down like a sine wave over the course of thousands of light-years. Astronomers aren’t sure what could cause that, Veena says.
Source: Veena. et al. A kiloparsec-scale molecular wave in the inner galaxy: Feather of the Milky Way? Astrophysical Journal Lettersdoi:10.3847/2041-8213/ac341f.