Sagittarius Dwarf Irregular Galaxy

Not to be confused with the Sagittarius Dwarf Spheroidal Galaxy.
SagDIG

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]
Apparent magnitude (V) 15.5[1]
Characteristics
Type IB(s)m[1] V (Dwarf irregular galaxy)
Apparent size (V) 2′.9 × 2′.1[1]
Other designations
Sagittarius Dwarf Irregular,[1] SGR Dwarf,[1]
ESO594-G004,[1] PGC 63287,[1] Kowal's Object[1]

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 thought to be the member of the Local Group most remote from the Local Group’s barycenter. 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[5] 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 billion years for the dominant population.[6]

References

  1. 1 2 3 4 5 6 7 8 9 10 11 "NASA/IPAC Extragalactic Database". Results for Sagittarius Dwarf Irregular. Retrieved 2007-03-15.
  2. ↑ I. D. Karachentsev; V. E. Karachentseva; W. K. Hutchmeier; D. I. Makarov (2004). "A Catalog of Neighboring Galaxies". Astronomical Journal. 127 (4): 2031–2068. Bibcode:2004AJ....127.2031K. doi:10.1086/382905.
  3. ↑ Karachentsev, I. D.; Kashibadze, O. G. (2006). "Masses of the local group and of the M81 group estimated from distortions in the local velocity field". Astrophysics. 49 (1): 3–18. Bibcode:2006Ap.....49....3K. doi:10.1007/s10511-006-0002-6.
  4. ↑ van den Bergh, Sidney (April 2000). "Updated Information on the Local Group". The Publications of the Astronomical Society of the Pacific. 112 (770): 529–536. Bibcode:2000PASP..112..529V. arXiv:astro-ph/0001040 Freely accessible. doi:10.1086/316548.
  5. ↑ Momany et al. 2005.
  6. ↑ Gullieuszik, M.; Rejkuba, M.; Cioni, M. R.; Habing, H. J.; Held, E. V. (November 2007). "Near-infrared photometry of carbon stars in the Sagittarius dwarf irregular galaxy and DDO 210". Astronomy and Astrophysics. 475 (2): 467–477. Bibcode:2007A&A...475..467G. arXiv:0709.0918 Freely accessible. doi:10.1051/0004-6361:20066848.

Coordinates: 19h 29m 59.0s, −17° 40′ 41″

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