Canes Venatici II orCVn II is adwarf spheroidal galaxy situated in theCanes Venaticiconstellation and discovered in 2006 in data obtained by theSloan Digital Sky Survey.[2] The galaxy is located at a distance of about 150 kpc from theSun and moves towards the Sun with the velocity of about 130 km/s.[2][6] It is classified as adwarf spheroidal galaxy (dSph) meaning that it has an elliptical (ratio of axes ~ 2:1) shape with a half-light radius of about74+14 −10 pc.[4]
CVn II is one of the smallest and faintest satellites of theMilky Way—its integrated luminosity is about 8,000 times that of the Sun (absolutevisible magnitude of about −4.9), which is much lower than the luminosity of a typicalglobular cluster.[4] However, its mass is about 2.5 millionsolar masses, which means that itsmass to light ratio is around 340. A high mass to light ratio implies that CVn II is dominated bydark matter.[6]
The stellar population of CVn II consists mainly of old stars formed more than 12 billion years ago.[3] 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.[7] The stars of CVn II were probably among the first stars to form in theUniverse. Currently there is no star formation in CVn II. Measurements have so far failed to detectneutral hydrogen in it—the upper limit is14000 solar masses.[8]
^abcdeBelokurov, V.; Zucker, D. B.; Evans, N. W.; Kleyna, J. T.; Koposov, S.; Hodgkin, S. T.; Irwin, M. J.;Gilmore, G.; Wilkinson, M. I.; Fellhauer, M.; Bramich, D. M.; Hewett, P. C.; Vidrih, S.; De Jong, J. T. A.; Smith, J. A.; Rix, H. -W.; Bell, E. F.; Wyse, R. F. G.; Newberg, H. J.; Mayeur, P. A.; Yanny, B.;Rockosi, C. M.; Gnedin, O. Y.; Schneider, D. P.; Beers, T. C.; Barentine, J. C.; Brewington, H.; Brinkmann, J.; Harvanek, M.; Kleinman, S. J. (2007). "Cats and Dogs, Hair and a Hero: A Quintet of New Milky Way Companions".The Astrophysical Journal.654 (2):897–906.arXiv:astro-ph/0608448.Bibcode:2007ApJ...654..897B.doi:10.1086/509718.S2CID18617277.
