Canes Venatici I (dwarf galaxy)

Canes Venatici I (dwarf galaxy)

Canes Venatici Dwarf Galaxy[1]
Observation data (J2000 epoch)
Constellation Canes Venatici
Right ascension 13h 28m 03.5s[1]
Declination +33° 33′ 21″[1]
Distance

711 ± 33 kly (218 ± 10 kpc)
[2]

685+23
−16
kly (210+7
−5
kpc)
[3]
Type dSph
Apparent dimensions (V) 17.8 ± 0.8′[4]
Apparent magnitude (V) 13.9 ± 0.5[5]
Other designations
CVn Dwarf Galaxy,[1] PGC 4689223

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.[5] It is one of the most distant satellites of the Milky Way as of 2011 together with Leo I and Leo II.[5] The galaxy is located at the distance of about 220 kpc from the Sun and moves away from the Sun with the velocity of about 31 km/s.[6] 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.[5][4]

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).[4] However, its mass is about 27 million solar 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.[6]

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.[7] There are also about 60 RR Lyrae stars.[3] 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.[2] 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.[8]

References

  1. ^ a b c d
  2. ^ a b
  3. ^ a b
  4. ^ a b c
  5. ^ a b c d
  6. ^ a b
  7. ^
  8. ^

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

References