Canes Venatici I dwarf galaxy

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Galaxy
Canes Venatici I dwarf galaxy
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AladinLite
Constellation Hunting dogs
Position
equinox :  J2000.0 , epoch : J2000.0
Right ascension 13 h 28 m 03.5 s
declination 33 ° 33 ′ 21 ″
Appearance
Morphological type dSph  
Brightness  (visual) (13.9 ± 0.5) mag
Angular expansion (17.8 ± 0.8) ′
Physical data
Affiliation Local group  
Radial velocity 116 km / s  
distance (711,000 ± 33,000) ly /
(218,000 ± 10,000) pc
Absolute brightness −8.6 mag
Metallicity [Fe / H] −2.08 ± 0.02
history
Discovery date 2006
Catalog names

Canes Venatici I or CVn I is a spheroidal dwarf galaxy (dSph) in the constellation of the hounds . It was in 2006 in recordings of the screening of the Sloan Digital Sky Survey discovered. As of 2011, it is one of the most distant satellite galaxies in our Milky Way together with Leo I and Leo II .

The galaxy is about 220 k pc from our solar system and has an escape velocity of approximately 31 km / s .
It has an aspect ratio of 2.5 to 1 and a half light radius of about 550 pc.

properties

Luminosity

CVn I is a relatively faint satellite of the Milky Way. The integral luminosity , with its absolute brightness of −8.6 m, is just 230,000 times that of the sun . In contrast, the total mass corresponds to approximately 27 million solar masses. This gives the dwarf galaxy a mass-luminosity ratio of around 220. This high ratio is an indication of a strong dominance of dark matter in this galaxy.

Metallicity

The star population of CVn I is predominantly dominated by ancient stars that were formed 10 billion years ago. The metallicity of this old generation is also very low with its [Fe / H] ≈ −2.08 ± 0.02 . In comparison, the sun contains about 110 times more heavy elements . CVn I also contains about 60 RR Lyrae stars.
The dwarf galaxy also contains a small proportion of younger stars around 1 to 2 billion years old. This generation is characterized by a metallicity of [Fe / H] ≈ −1.5 , accounts for about 5 % of the mass and 10% of the light of the galaxy and is concentrated towards the center of the galaxy. At the moment there is no star formation in CVn I ; no neutral hydrogen gas could be found in the measurements so far (upper limit for this in about 30,000 solar masses).

Web links

Commons : Constellation Hounds  - Collection of images, videos and audio files

Individual evidence

  1. ↑ a b SIMBAD Astronomical Database. In: Results for Canes Venatici Dwarf. Retrieved November 21, 2011 .
  2. ↑ a b c d e sugar, DB; Belokurov, V .; Evans, NW; Kleyna, JT; Irwin, MJ; Wilkinson, MI; Fellhauer, M .; Bramich, DM et al .: A New Milky Way Dwarf Satellite in Canes Venatici . In: Astrophysical Journal . 643 (2): L103, 2006. doi : 10.1086 / 505216 .
  3. ↑ a b c Martin, NF; De Jong, JTA; Rix, HW: A Comprehensive Maximum Likelihood Analysis of the Structural Properties of Faint Milky Way Satellites . In: Astrophysical Journal . 684 (2): 1075, 2008. doi : 10.1086 / 590336 .
  4. ↑ a b Martin, NF; Coleman, MG; De Jong, JTA; Rix, HW; Bell, EF; Sand, dj; Hill, JM; Thompson, D. et al .: A Deep Large Binocular Telescope View of the Canes Venatici I Dwarf Galaxy . In: Astrophysical Journal . 672: L13, 2008. doi : 10.1086 / 525559 .
  5. ↑ a b Kirby, EN; Simon, JD; Geha, M .; Guhathakurta, P .; Frebel, A .: Uncovering Extremely Metal-Poor Stars in the Milky Way's Ultrafaint Dwarf Spheroidal Satellite Galaxies . In: Astrophysical Journal . 685: L43, 2008. doi : 10.1086 / 592432 .
  6. ↑ a b Simon, JD; Geha, M .: The Kinematics of the Ultra ‐ faint Milky Way Satellites: Solving the Missing Satellite Problem . In: Astrophysical Journal . 670: 313, 2007. doi : 10.1086 / 521816 .
  7. ↑ Kirby, EN; Simon, JD; Geha, M .; Guhathakurta, P .; Frebel, A .: Variable Stars in the Newly Discovered Milky Way Dwarf Spheroidal Satellite Canes Venatici I . In: Astrophysical Journal . 674 (2): L81, 2008. doi : 10.1086 / 529137 .
  8. ↑ Grcevich, J .; Putman, ME: HI in Local Group Dwarf Galaxies and Stripping by the Galactic Halo . In: Astrophysical Journal . 696: 385, 2009. doi : 10.1088 / 0004-637X / 696/1/385 .