Cassiopeia Dwarf

The Cassiopeia Dwarf (also known as Andromeda VII) is a dwarf spheroidal galaxy about 2.58 Mly away in the constellation Cassiopeia. The Cassiopeia Dwarf is part of the Local Group and a satellite galaxy of the Andromeda Galaxy (M31).

"Andromeda 7" redirects here. For the star, see 7 Andromedae.
Cassiopeia Dwarf
Cassiopeia Dwarf by HST/WikiSky
Observation data (J2000 epoch)
ConstellationCassiopeia
Right ascension 23h 26m 31.0s[1]
Declination+50° 41′ 31″[1]
Redshift-307 ± 2 km/s[1]
Distance2.58 ± 0.13 Mly (790 ± 40 kpc)[2][3]
Apparent magnitude (V)12.9[1]
Characteristics
TypeSph?[1]
Apparent size (V)2′.5 × 2′.0[1]
Notable featuressatellite galaxy of the Andromeda Galaxy
Other designations
Andromeda VII, And VII, Cas dSph, PGC 2807155, Cassiopeia Dwarf Galaxy[1][4]

The Cassiopeia Dwarf was found in 1998, together with the Pegasus Dwarf, by a team of astronomers (Karachentsev and Karachentseva)[5] in Russia and Ukraine. The Cassiopeia Dwarf and the Pegasus Dwarf are farther from M31 than its other known companion galaxies, yet still appear bound to it by gravity. Neither galaxy contains any young, massive stars or shows traces of recent star formation. Instead, both seem dominated by very old stars, with ages of up to 10 billion years.

See also
  • Andromeda's satellite galaxies

References
  1. "NASA/IPAC Extragalactic Database". Results for Cassiopeia Dwarf. Retrieved 2006-11-30.
  2. Karachentsev, I. D.; Karachentseva, V. E.; Hutchmeier, W. K.; Makarov, D. I. (2004). "A Catalog of Neighboring Galaxies". Astronomical Journal. 127 (4): 2031–2068. Bibcode:2004AJ....127.2031K. doi:10.1086/382905.
  3. Karachentsev, I. D.; Karachentseva, V. E. (1999). "New probable companions to M 31 found on the POSS-II". Astronomy and Astrophysics. 341 (1): 355–356. Bibcode:1999A&A...341..355K.
  4. "NAME Andromeda VII". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2010-03-06.
  5. Pritzl, Barton J.; Armandroff, Taft E.; Jacoby, George H.; Da Costa, G. S. (May 2005). "The Dwarf Spheroidal Companions to M31: Variable Stars in Andromeda I and Andromeda III". The Astronomical Journal. 129 (5): 2232–2256. arXiv:astro-ph/0501083. Bibcode:2005AJ....129.2232P. doi:10.1086/428372.

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