Dark galaxies

hypothesized galaxy consisting mainly of dark matter with no, or very few, stars

VIRGOHI21 is an extended region of neutral hydrogen (HI) in the Virgo Cluster discovered in 2005. Analysis of its internal motion indicates that it may contain a large amount of dark matter, as much as a small galaxy. Since VIRGOHI21 apparently contains no stars, this would make it one of the first detected dark galaxies. Skeptics of this interpretation argue that VIRGOHI21 is simply a tidal tail of the nearby galaxy NGC 4254.

high-velocity cloud

galaxy

Galaxy in the constellation Haar der Berenike

Candidate Dark Galaxy 2 (CDG-2) is a candidate for a dark galaxy, composed predominantly of dark matter, along with four globular clusters, in the Perseus cluster. It'd be one of the most dark matter dominated galaxies probably detected, estimated to be between 99.94% and 99.98% dark matter. It has been not confirmed yet if it's a true dark galaxy, more studies are required for a definitive conclusion.

high-velocity cloud in the constellation Pisces