Canes Venatici II

CVn II is one of the smallest and faintest satellites of the Milky Way—its integrated luminosity is about 8,000 times that of the Sun (absolute visible magnitude of about −4.9), which is much lower than the luminosity of a typical globular cluster. However, its mass is about 2.5 million solar masses, which means that its mass to light ratio is around 340. A high mass to light ratio implies that CVn II is dominated by dark matter.

The stellar population of CVn II consists mainly of old stars formed more than 12 billion years ago. The metallicity of these old stars is also very low at [Fe/H] ≈ −2.19±0.58, which means that they contain 150 times less heavy elements than the Sun. The stars of CVn II were probably among the first stars to form in the Universe. Currently there is no star formation in CVn II. Measurements have so far failed to detect neutral hydrogen in it—the upper limit is 14000 solar masses.