New images of the Arches Cluster, one of the most chaotic and densely packed parts of the galaxy, have revealed that the distribution of stars there look surprisingly similar to that of our own relatively quiet part of the Milky Way.
Astronomers were able to use Europe's Very Large Telescope to get unprecedentedly sharp pictures of the Arches Cluster. Located some 25,000 lightyears away near the supermassive black hole at the center of our galaxy, Arches has the densest distribution of stars of any part of the Milky Way. Only three lightyears across, each cubic lightyear has well over a thousand stars. As a point of comparison, our closest neighboring star system, Alpha Centauri, is 4.37 lightyears away, making it further away from us than the entire length of the Arches Cluster.
For years, the cluster seemed to be the lone exception to a universal law governing the distribution of stars, with higher mass stars far less common than their lower mass counterparts. The very young stars in the Arches Cluster - they are only about 2.5 million years old, compared to the Sun's 4.57 billion year age - had appeared to be mostly high mass stars. This had led astronomers to conclude the unimaginable density of the system affected the formation of stars, but that no longer appears to be the case. As such, the law of star distribution really does appear to be universal in nature after all.
Even so, the Arches Cluster is still very much a galactic oddity. It is under tremendous gravitational pressures from the neighboring black hole, as well as other neighboring stars and gas, and it is ten times denser than a normal star cluster of the same age. Notwithstanding the discovery of the expected distribution of bigger and smaller stars, the Arches Cluster provides one of the best laboratories for observing the formation of massive stars in one of the galaxy's most chaotic environments, and that will be the emphasis of the astronomers' investigations going forward.