Cassiopeia Dwarf
Cassiopeia Dwarf by HST/WikiSky
Observation data (J2000 epoch)
Constellation	Cassiopeia
Right ascension	23h 26m 31.0s[1]
Declination	+50° 41′ 31″[1]
Redshift	−307 ± 2 km/s[1]
Distance	2.45 Mly (0.75 Mpc)[2]
Apparent magnitude (V)	12.9[1]
Absolute magnitude (V)	−13.3 ± 0.3[2]
Characteristics
Type	dSph[2]
Apparent size (V)	2.5′ × 2.0′[1]
Notable features	satellite galaxy of the Andromeda Galaxy
Other designations
Andromeda VII, And VII, Cas dSph, PGC 2807155, Cassiopeia Dwarf Galaxy[1][3]

The Cassiopeia Dwarf (also known as Andromeda VII) is a dwarf spheroidal galaxy about 2.45 Mly away in the constellation Cassiopeia.^[2] The Cassiopeia Dwarf is part of the Local Group and a satellite galaxy of the Andromeda Galaxy (M31). In the sky, it appears behind the Milky Way's galactic plane, and so it is reddened by 0.194 magnitudes.^[2] With a luminosity of 1.8×10⁷ L_☉ and a stellar mass of 19.73×10⁶ M_☉, it is the brightest and most massive of the Andromeda Galaxy's dwarf spheroidal galaxy satellites. It also has the highest metallicity out of all of them.^[2]

The Cassiopeia Dwarf was found in 1998, together with the Pegasus Dwarf, by a team of astronomers (Karachentsev and Karachentseva)^[4] 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. The main period of star formation occurred around 6.2 billion years ago, and 90% of the star formation in the Cassiopeia Dwarf was done by 5 billion years ago.^[2]

• Andromeda's satellite galaxies

• SEDS: Dwarf Spheroidal Galaxy Andromeda VII
• The Cassiopeia Dwarf on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images

v t e Andromeda Galaxy
Location	Andromeda Galaxy → Andromeda subgroup → Local Group → Local Sheet → Virgo Supercluster → Laniakea Supercluster → Local Hole → Observable universe → Universe Each  → may be read as "within" or "part of".
Satellite galaxies	M32 M110 NGC 185 NGC 147 Andromeda I Andromeda II Andromeda III Andromeda IV* Andromeda V Andromeda VI Andromeda VII Andromeda VIII Andromeda IX Andromeda X Andromeda XI Andromeda XII Andromeda XIII Andromeda XIV Andromeda XV Andromeda XVI Andromeda XVII Andromeda XVIII Andromeda XIX Andromeda XX Andromeda XXI Andromeda XXII Andromeda XXIII Andromeda XXIV Andromeda XXV Andromeda XXVI Andromeda XXVII Andromeda XXVIII Andromeda XXIX Triangulum subgroup* *It is uncertain whether these are companion galaxies of the Andromeda Galaxy
Catalogued stars	AE Andromedae AF Andromedae M31-RV
Other	Andromeda–Milky Way collision S Andromedae Mayall II M32p NGC 206 3XMM J004232.1+411314
Category