Canes Venatici I
Template:Short description Template:Infobox Galaxy
Canes Venatici I or CVn I is a dwarf spheroidal galaxy situated in the Canes Venatici constellation and discovered in 2006 in the data obtained by Sloan Digital Sky Survey.[1] It is one of the most distant known satellites of the Milky Way as of 2011 together with Leo I and Leo II.[1] The galaxy is located at a distance of about 220 kpc from the Sun and is moving away from the Sun at a velocity of about 31 km/s.[2] 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.[1][3]
CVn I is a relatively faint satellite of the Milky Way—its integrated luminosity is about 230,000 times that of the Sun (absolute visible magnitude of about −8.6).[3] However, its mass is about 27 million solar masses, which means that the galaxy's mass to light ratio is around 220. A high mass to light ratio implies that CVn I is predominately made up of dark matter.[2]
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 contain 110 times less heavy elements than the Sun.[4] There are also about 60 RR Lyrae stars.[5] 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.[6] There is currently no star formation in CVn I and the measurements have so far failed to detect neutral hydrogen in it—the upper limit is 30,000 solar masses.[7]
References
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External links
- The Universe within 500000 light-years The Satellite Galaxies (Atlas of the Universe)
- Two New Galaxies Orbiting the Milky Way (Ken Croswell) April 19, 2006
- Strange satellite galaxies revealed around Milky Way Kimm Groshong (New Scientist) 17:00 24 April 2006
- New Milky Way companions found: SDSS-II first to view two dim dwarf galaxies (SDSS) May 8, 2006
- Astronomers Find Two New Milky Way Companions (SpaceDaily) May 10, 2006
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