Hounds Dogs II or CVn II is a dwarf spheroidal galaxy located in the constellation Hounds Dogs . It was discovered in 2006 according to data obtained by Sloan's digital sky survey [3] . The galaxy is located at a distance of about 150 kpc from the Sun and moves toward the Sun at a speed of about 130 km / s [3] [5] . It is classified as a dwarf spheroidal galaxy (dSph). This means that it has an elliptical shape (axis ratio ~ 2: 1) with effective radius of about 74 +14
β10 pc [6]
| Hounds Dogs II [1] | |
|---|---|
| Galaxy | |
| Research history | |
| Discoverer | |
| opening date | 2006 |
| Observational data ( Age J2000 ) | |
| Constellation | Hounds Dogs |
| Right ascension | |
| Declination | |
| Apparent magnitude m V | |
| Characteristics | |
| Type of | dSph [3] |
| Included in | |
| Radial velocity | |
| Distance | 490 +49 β13 thousand St. years (160 +4 β5 kpc ) [4] |
| The properties | subgroup of the milky way |
CVn II is one of the smallest and faintest satellites of the Milky Way - its integral luminosity is only 8,000 times greater than the Sun (absolute apparent magnitude is about β4.9), which is much lower than the luminosity of a typical globular cluster [6] . However, its mass is about 2.5 million solar masses, which means that the mass-luminosity ratio for it is about 340. A large value of this parameter means that Dark Matter dominates in the Hounds Dogs [5] .
The stellar population of CVn II consists mainly of old stars formed over 12 billion years ago [4] . The metallicity of these old stars is very low: [Fe / H] β β2.19 Β± 0.58 , which means that they contain 150 times less heavy elements than the Sun [7] . The Stars of the Hounds of Dogs II was probably one of the first stars formed in the Universe. There is currently no star formation in CVn II. Measurements have so far failed to detect a neutral hydrogen radio line in it - the upper limit is 14,000 solar masses [8] .
Notes
- β SIMBAD Astronomical Database . Results for CVN II Dwarf Galaxy . Date of treatment February 6, 2010. Archived June 2, 2013.
- β 1 2 McConnachie A. W. THE OBSERVED PROPERTIES OF DWARF GALAXIES IN AND AROUND THE LOCAL GROUP // Astron. J. / J. G. III - IOP Publishing , 2012 .-- Vol. 144, Iss. 1. - P. 4. - ISSN 0004-6256 ; 1538-3881 - doi: 10.1088 / 0004-6256 / 144/1/4
- β 1 2 3 4 Belokurov V. , Zucker DB , Evans NW , Kleyna JT , Koposov S. , Hodgkin ST , Irwin MJ , Gilmore G. , Wilkinson MI , Fellhauer M. , Bramich DM , Hewett PC , Vidrih S. , De Jong JTA , Smith JA , Rix H.βW. , Bell EF , Wyse RFG , Newberg HJ , Mayeur PA , Yanny B. , Rockosi CM , Gnedin OY , Schneider DP , Beers TC , Barentine JC , Brewington H. , Brinkmann J. , Harvanek M. , Kleinman SJ , Krzesinski J. , Long D. , Nitta A. , Snedden SA Cats and Dogs, Hair and a Hero: A Quintet of New Milky Way Companions // The Astrophysical Journal. - 2007. - January 10 ( t. 654 , No. 2 ). - S. 897β906 . - ISSN 0004-637X . - DOI : 10.1086 / 509718 .
- β 1 2 Greco, Claudia; Dall'Ora, Massimo; Clementini, Gisella et al. On the Newly Discovered Canes Venatici II dSph Galaxy (Eng.) // The Astrophysical Journal : journal. - IOP Publishing 2008. - Vol. 675 , no. 2 . - P. L73 β L76 . - DOI : 10.1086 / 533585 . - . - arXiv : 0712.2241 .
- β 1 2 Simon Joshua D. , Geha Marla. The Kinematics of the Ultra β faint Milky Way Satellites: Solving the Missing Satellite Problem // The Astrophysical Journal. - 2007. - November 20 ( t. 670 , No. 1 ). - S. 313-331 . - ISSN 0004-637X . - DOI : 10.1086 / 521816 .
- β 1 2 Martin Nicolas F. , de Jong Jelte TA , Rix Hans β Walter. A Comprehensive Maximum Likelihood Analysis of the Structural Properties of Faint Milky Way Satellites // The Astrophysical Journal. - 2008. - September 10 ( t. 684 , No. 2 ). - S. 1075-1092 . - ISSN 0004-637X . - DOI : 10.1086 / 590336 .
- β Kirby Evan N. , Simon Joshua D. , Geha Marla , Guhathakurta Puragra , Frebel Anna. Uncovering Extremely Metal-Poor Stars in the Milky Way's Ultrafaint Dwarf Spheroidal Satellite Galaxies // The Astrophysical Journal. - 2008. - September 5 ( t. 685 , No. 1 ). - S. L43 β L46 . - ISSN 0004-637X . - DOI : 10.1086 / 592432 .
- β Grcevich Jana , Putman Mary E. HI IN LOCAL GROUP DWARF GALAXIES AND STRIPPING BY THE GALACTIC HALO // The Astrophysical Journal. - 2009. - April 15 ( t. 696 , No. 1 ). - S. 385-395 . - ISSN 0004-637X . - DOI : 10.1088 / 0004-637X / 696/1/385 .