M19

M19 is the most flattened globular cluster known. This deformation of the cluster from its globular shape may be related to its proximity to the center of the Galaxy, only 5,200 light-years away.

M19 is quite abundant and dense, and is considerably concentrated. Considering the distance between us and its apparent size, it corresponds to a size of 140 light-years along its main axis.

According to a study published in 2015, M19 belongs to a new class of globular clusters that the authors called "iron complex clusters." These clusters are distinguished from others by a wide dispersion of metallicity. M19 is composed of at least two distinct stellar populations. Other clusters in this category, such as Omega Centauri, M2, M22, NGC 5286, and M62, can also be added to this list.