Canes Venatici I

Canes Venatici I or CVn I is a dwarf spheroidal galaxy and one the most distant satellites of the Milky Way together with Leo I and Leo II. The galaxy is located at the distance of about 220 kpc. It is classified as a dwarf spheroidal galaxy (dSph) meaning that it has an elliptical (ratio of axes ~ 2.5:1) shape with the half-light radius of about 550 pc.

CVn I is a relatively faint satellite of the Milky Way, with an absolute visible magnitude of about −8.6. Its mass is about 27 million stellar masses, which means that galaxy's mass to light ratio is around 220. A high mass to light ratio implies that CVn I is dominated by the dark matter.

The stellar population of CVn I consists mainly of old stars formed more than 10 billion years ago. The metallicity of these old stars is also very low at [Fe/H] ≈ −2.08 ± 0.02, which means that they less heavy elements. There are also about 60 RR Lyrae stars. The galaxy also contains a small fraction of younger (1–2 billion years old) more metal rich ( [Fe/H] ≈ −1.5) stars, which account for about 5% of its mass and 10% of its light. These younger stars are concentrated in the center of the galaxy.

There is currently no star formation in CVn I and the measurements have so far failed to detect neutral hydrogen in it.