Title: A High Stellar Velocity Dispersion and ~100 Globular Clusters for the Ultra Diffuse Galaxy Dragonfly 44
Publication: ApJ, v828, Number 1, arXiv: 1606.06291
The title of this paper sounds like some standard astrophysics analyses; but, dig a little deeper and you’ll find – what I think – is an incredibly interesting, surprising and unexpected observation.
The Coma Cluster: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
Last year, using the WM Keck Observatory and the Gemini North Telescope in Manuakea, Hawaii, the Dragonfly Telephoto Array observed the Coma cluster (a large cluster of galaxies in the constellation Coma – I’ve included a Hubble Image to the left). The team identified a population of large, very low surface brightness (ie: not a lot of stars), spheroidal galaxies around an Ultra Diffuse Galaxy (UDG) called Dragonfly 44 (shown below). They determined that Dragonfly 44 has so few stars that gravity could not hold it together – so some other matter had to be involved – namely DARK MATTER (my favorite kind of unknown matter).
The ultra-diffuse galaxy Dragonfly 44. The galaxy consists almost entirely of dark matter. It is surrounded by faint, compact sources. Image credit: Pieter van Dokkum ...