Sagittarius Dwarf Irregular Galaxy

Not to be confused with the Sagittarius Dwarf Elliptical Galaxy.
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]

References

  1. ^ a b c d e f g h i j k "NASA/IPAC Extragalactic Database". Results for Sagittarius Dwarf Irregular. http://nedwww.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=Sagittarius+Dwarf+Irregular#ObjNo1. 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. arXiv:astro-ph/0001040. Bibcode 2000PASP..112..529V. doi:10.1086/316548. 
  5. ^ 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. doi:10.1051/0004-6361:20066848. 

External links

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