These aren't the galaxies you're looking for

Looks like I need to add this one to my reading list.

The three ultra-faint dwarf galaxy suspects, DES1, Eridanus III, and Tucana V, located in the vicinity of the Magellanic Clouds, were studied using a wide array of classification techniques. For each, fundamental properties including age, mass, luminosity, metallicity (ratio of heavier elements) and distance were determined. Based upon these parameters, the objects have instead been classified as star clusters.

Classification of these faint objects as star clusters implies that they are not dominated by dark matter, as dwarf galaxies typically are, “and so we are still trying to define ultra-faint dwarf galaxies. Where are these smallest galaxies, what are their properties and how many are there? Answering these questions will help complete the census of Milky Way satellites and let us understand the history of our galaxy.”, says Conn.

Conn and his team are looking into the “Missing Satellites” problem which was originally identified almost two decades ago. Based on what is called the hierarchical formation scenario, many astronomers expected a large number of dwarf satellite galaxies, each containing a high fraction of dark matter, surrounding larger galaxies like our Milky Way. However, too few such satellites have been found to account for the expected amounts of dark matter. Thus, classifying these ultra-faint objects is crucial to our understanding of dark matter in the Universe.

I'm instantly nervous about classifying the dynamical nature of objects based on their other properties, but I'll give the paper a read in due course.

https://www.gemini.edu/node/21044