While the universe is a pretty wide-open territory with plenty of available real estate for stars to settle, student astronomers have recently cataloged a cramped cluster of two ultra-compact galaxies with stars existing in close proximity to each other.
Discovered by undergrad physics students Michael Sandoval and Richard Vo of San José State University from data buried deep in images captured by the Apache Point Observatory's Sloan Digital Sky Survey, this pair of record-breaking compact star systems are highly rare and similar to normal globular clusters, but shine up to a thousand times brighter and a million times more dense!
Named Ultra-Compact Dwarfs (UCD), these brilliant stellar clusters were found orbiting larger host galaxies and are thought to be the ancient remains of once-normal galaxies that were swallowed up by the ravenous host, leaving only the dense gatherings near the center. Sandoval and Vo confirmed their observational findings with the Subaru Telescope, Hubble Space Telescope, and spectroscopy from the Goodman Spectrograph located on the Southern Astrophysical Research Telescope.
M59-UCD3 ,the initial system discovered, has a width 200 times smaller than the Milky Way, but with an incredible stellar density 10,000 times greater than what we would normally observe in our familiar stretch of the heavens.. The second ultra-compact dwarf, now known as M85-HCC1, is similar in size, but is even more dazzling; displaying a stellar density a million times greater than what we view here on Earth.
“This hypercompact cluster is by far the densest confirmed free-floating stellar system, and is equivalent to the densest known nuclear star clusters,” declared both researchers in their illuminating study, soon available at the Astrophysical Journal Letters.
Sandoval's animated simulation below depicts this stripping theory to show the possible formation of an ultra-dense galaxy:
Whether these ultra-compact dwarf galaxies are the remnant cores of stripped dwarf galaxies, formed by the marriage of other superclusters, or the result of overweight supermassive black holes remains a mystery to be theorized over for decades to come. Any bright ideas as to their origins?