SagDIG | |
---|---|
SagDIG by Hubble Space Telescope |
|
Observation data (J2000 epoch) | |
Constellation | Sagittarius |
Right ascension | 19h 29m 59.0s[1] |
Declination | -17° 40′ 41″[1] |
Redshift | -79 ± 1 km/s[1] |
Distance | 3.39 ± 0.23 Mly (1.04 ± 0.07 Mpc)[2][3] |
Type | IB(s)m[1] V (Dwarf irregular galaxy) |
Apparent dimensions (V) | 2′.9 × 2′.1[1] |
Apparent magnitude (V) | 15.5[1] |
Other designations | |
Sagittarius Dwarf Irregular,[1] SGR Dwarf,[1] ESO594-G004,[1] PGC 63287,[1] Kowal's Object[1] |
|
See also: Galaxy, List of galaxies |
The Sagittarius Dwarf Irregular Galaxy or SagDIG is a dwarf galaxy in the constellation of Sagittarius. It lies about 3.4 million light-years away. SagDIG should not be confused with the Sagittarius Dwarf Elliptical Galaxy or SagDEG, a satellite galaxy of the Milky Way. It was discovered by Cesarsky et al. on a photographic plate taken for the ESO (B) Atlas on June 13, 1977 using the ESO 1 meter Schmidt telescope.
The SagDIG is the most remote object from the barycenter thought to be a member of the Local Group. It is only slightly outside the zero-velocity surface of the Local Group.[4]
SagDIG is a much more luminous galaxy than Aquarius Dwarf and it has been through a prolonged star formation (Momany et al. 2005). This has resulted in it containing a rich intermediate-age population of stars. Twenty-seven candidate carbon stars have been identified inside SagDIG. Analysis shows that the underlying stellar population of SagDIG is metal-poor (at least [Fe/H] ≤ −1.3). Further, the population is young, with the most likely average age between 4 and 8 Gyr for the dominant population.[5]