Coma Berenices dwarf galaxy

Database links to Coma Berenices dwarf galaxy

Galaxy Coma Berenices dwarf galaxy
Coma Berenices dwarf galaxy
AladinLite
Constellation	Berenike's hair
Position equinox :  J2000.0 , epoch : J2000.0
Right ascension	12 h 26 m 59 s
declination	23 ° 55 ′ 09 ″
Appearance
Morphological type	dSph
Brightness  (visual)	14.5 ± 0.5 mag
Angular expansion	11.8 ′
Physical data
Affiliation	Local group
distance	(143,000 ± 13,000) (137,000 ± 5,000) ly / (44,000 ± 4,000) (42,000 ± 2,000) pc
history
Discovery date	2006
Catalog names
Com, Coma Dwarf

The Coma-Berenices dwarf galaxy , also Com for short , is a spheroidal dwarf galaxy in the constellation Haar der Berenike . It was in the year 2006 in photographs of the screening of the Sloan Digital Sky Survey discovered.

properties

Sizes

The galaxy is in a distance of about 44 k pc to our solar system and moves away from our sun at a speed of about 98 km / s . It has an ellipsoidal shape with an axis ratio of about 5: 3 and a half-light radius of 70 pc.

Luminosity

Com is one of the smallest and faintest satellite galaxies in our Milky Way (only Segue 1 , Segue 2 , Bootes II and Willman 1 are fainter). The integral luminosity, with an absolute brightness of M _V = -4.1 ^m , is roughly 3,700 times that of the sun, which is less than the brightness of the majority of globular clusters . Nevertheless, the dwarf galaxy has a total mass of around 1.2 million solar masses due to a high mass-luminosity ratio of 450 . This implies a dominance by dark matter that is not untypical for this type of galaxy .

Metallicity

The star population of the Coma Berenices dwarf galaxy is mainly composed of older stars that formed more than 12 billion years ago. The metallicity of this old generation of stars is correspondingly low with [Fe / H] = −2.53 ± 0.45 , ie it has only one 350th of elements compared to the sun.

The stars of this dwarf galaxy are probably among the first stars ever to have formed in the universe . Currently, no star formation can be determined in this galaxy, the lower limit of measurement for neutral hydrogen gas is 46 M _☉ .

origin

The Coma dwarf is located near the Sagittarius Current , which is made up of lost stars from the Sagittarius dwarf galaxy . This makes an earlier physical connection between these two galaxies likely.

Web links

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

Individual evidence

1. ↑ ^{a b c} SIMBAD Astronomical Database . In: Results for Coma Dwarf . Retrieved February 7, 2010.
2. ↑ ^{a b c d e f g h} V. Belokurov, Zucker, DB; Evans, NW; Kleyna, JT; Koposov, S .; Hodgkin, ST; Irwin, MJ; Gilmore, G. et al .: Cats and Dogs, Hair and a Hero: A Quintet of New Milky Way Companions . In: The Astrophysical Journal . 654, No. 2, 2007, p. 897. doi : 10.1086 / 509718 .
3. ↑ Ilaria Musella, Ripepi, Vincenzo; Clementini, Gisella, et al. : Pulsating Variable Stars in the Coma Berenices Dwarf Spheroidal Galaxy . In: The Astrophysical Journal Letters . 695, No. 1, 2009, pp. L83-1L87. arxiv : 0902.4230 . bibcode : 2009ApJ ... 695L..83M . doi : 10.1088 / 0004-637X / 695/1 / L83 .
4. ↑ ^{a b} J. Simon, Geha, M .: The Kinematics of the Ultra ‐ faint Milky Way Satellites: Solving the Missing Satellite Problem . In: The Astrophysical Journal . 670, 2007, p. 313. doi : 10.1086 / 521816 .
5. ↑ ^{a b c} Martin N.F., De Jong, JTA; Rix, HW: A Comprehensive Maximum Likelihood Analysis of the Structural Properties of Faint Milky Way Satellites . In: The Astrophysical Journal . 684, No. 2, 2008, p. 1075. doi : 10.1086 / 590336 .
6. ↑ EN Kirby, Simon, JD; Geha, M .; Guhathakurta, P .; Frebel, A .: Uncovering Extremely Metal-Poor Stars in the Milky Way's Ultrafaint Dwarf Spheroidal Satellite Galaxies . In: The Astrophysical Journal . 685: L43, 2008. doi : 10.1086 / 592432 .
7. ↑ J. Grcevich, Putman, ME: HI in Local Group Dwarf Galaxies and stripping by the Galactic halo . In: The Astrophysical Journal . 696, 2009, p. 385. doi : 10.1088 / 0004-637X / 696/1/385 .
8. ↑ V. Belokurov, Walker, MG; Evans, NW et al. : Segue 2: A Prototype of the Population of Satellites of Satellites . In: Mon. Not. R. Astron. Soc. . 397, No. 4, 2009, pp. 1748-1755. arxiv : 0903.0818 . bibcode : 2009MNRAS.397.1748B . doi : 10.1111 / j.1365-2966.2009.15106.x .