Andromeda I
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| Andromeda I | |
| Observation data (J2000 epoch) | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 00h 45m 39.8s[1] |
| Declination | +38° 02′ 28″[1] |
| Redshift | -368 ± 11 km/s[1] |
| Distance | 2.64 ± 0.10 Mly (810 ± 30 kpc)[2][3] |
| Type | E3 pec?[1] |
| Apparent dimensions (V) | 2′.5 × 2′.5[1] |
| Apparent magnitude (V) | 13.6[1] |
| Notable features | satellite galaxy of M31 |
| Other designations | |
| And I,[2] Anon 0043+37,[1] PGC 2666[1] | |
| See also: Galaxy, List of galaxies | |
Andromeda I is a dwarf spheroidal galaxy(dSph)[4] about 2.64 million light-years away in the constellation Andromeda. Andromeda I is part of the Local group of galaxies and a satellite galaxy of the Andromeda Galaxy (M31). It is roughly 3.5 degrees south and slightly east of M31.
Andromeda I was discovered by Sidney van den Bergh[5] in 1970 with the Mount Palomar Observatory 48-inch telescope.[4] Further study of Andromeda I was done by the WFPC2 camera of the Hubble Space Telescope. This found that the horizontal branch stars, like other dwarf spheroidal galaxies were predominantly red. From this, and the abundance of blue horizontal branch stars, along with RR Lyrae stars, lead to the conclusion there was an extended epoch of star formation. The estimated age is approximately 10 Gyr. The Hubble telescope also found a globular cluster in Andromeda I, being the least luminous galaxy where such a cluster was found.
[edit] See also
[edit] References
- SEDS: Andromeda I
- Grebel, E. K.; Dolphin, A. E.; Guhathakurta, P. Discovery of a Globular Cluster in M31's Dwarf Spheroidal Companion Andromeda I (2000) The Publications of the Astronomical Society of the Pacific, Volume 112, Issue 770, pp. 529-536.
- Da Costa, G. S.; Armandroff, T. E.; Caldwell, Nelson; Seitzer, Patrick. The Dwarf Spheroidal Companions to M31: WFPC2 Observations of Andromeda I (1996) Astronomical Journal v.112, p.2576
- 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, <http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2000PASP..112..529V>
- ^ a b c d e f g h NASA/IPAC Extragalactic Database. Results for Andromeda I. Retrieved on 2008-01-21.
- ^ a b I. D. Karachentsev, V. E. Karachentseva, W. K. Hutchmeier, D. I. Makarov (2004). "A Catalog of Neighboring Galaxies". Astronomical Journal 127: 2031-2068. doi:.
- ^ 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. doi:.
- ^ a b van den Bergh, Sydney (January 1972), “Search for Faint Companions to M31”, Astrophysical Journal 171: L31, <http://adsabs.harvard.edu/abs/1972ApJ...171L..31V>
- ^ McConnachie, A. W.; Irwin, M. J.; Ferguson, A. M. N.; Ibata, R. A.; Lewis, G. F.; Tanvir, N. (2005). "Distances and metallicities for 17 Local Group galaxies". Monthly Notices of the Royal Astronomical Society 356 (4): 979-997. doi:.
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