This simulated image shows structures with low surface brightness in the halo surrounding a galaxy similar to the Milky Way. These structures appear as faint, luminous arcs extending from the galaxy’s central disk.
The structure of the galactic halo provides fundamental information about the process of galaxy formation. For example, stellar streams—such as the arcs seen in this image—are the remnants of smaller galaxies or star clusters that were torn apart and absorbed during their merger with the host galaxy.
The European Space Agency’s (ESA) ARRAKIHS mission plans to study the stellar halos of at least 80 nearby galaxies with masses similar to that of the Milky Way. This sample is large enough to provide statistical data on how a “typical” galaxy forms, which will allow us to better understand the extent to which our galaxy is unique.
