This Galaxy Is 15,000 Times More Dense Than the Milky Way

NASA astronomers say they have discovered what may be the densest galaxy in our tiny corner of the universe. Known as M60-UCD1, it's an ultra-compact dwarf galaxy sitting approximately 54 million light years away from Earth.

The Hubble Space Telescope was the first to spot M60-UCD1, which could definitely use a snazzier name. Additional studies were undertaken with the aid of the Chandra X-Ray Observatory and ground-based telescopes. Observation showed a stellar system that easily lends itself to superlatives.

It is one of the most massive galaxies of its type, and definitely the most lustrous. At an estimated age of 10 billion years old, it is about 50,000 light years across, with most of its contents crammed into a radius of about 80 of those light years. Its density is 15,000 times that of the Milky Way and it weighs more than 200 million suns, which is so unfathomable that it almost sounds like metaphor.

What's fascinating about the incredible density of this galaxy is how it got like that in the first place. A major question regarding M60-UCD1’s history is whether it was initially a "jam-packed star cluster" or if it was an even bigger galaxy in its distant past. According to a paper reviewing relevant research, "it is most plausible that the object is the tidally-stripped remnant of a more massive progenitor galaxy." In other words, M60-UCD1 may have one been 50 to 200 times its current size, but as time passed, stars were stripped away and the galaxy shrank.

This hypothesis is supported by three factors: the mass of M60-UCD1, the notable amount of heavy elements within the galaxy, and the fact that the center may, according to x-ray data from the Chandra X-Ray Observatory, be an enormous black hole. If proved, the latter would indicate that M60-UCD1 was not a star cluster because, as NASA itself noted, "large black holes are not found in star clusters… it was likely produced by collisions between M60-UCD1 and one or more nearby galaxies."

Beyond the impressive stats, it’s also possible that this galaxy could hold the possibility for life. It is solely speculation at this point, but according to Anil Seth, one of the co-authors on tthe paper, the large quantity of heavy elements “makes it a fertile environment for planets and, potentially, for life to form.”