Astronomy:Pisces Dwarf

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Pisces Dwarf
Hubble Space Telescope image of the Pisces Dwarf
Observation data (J2000 epoch)
ConstellationPisces
Right ascension 01h 03m 55.0s[1]
Declination+21° 53′ 06″[1]
Redshift-287 ± 0 km/s[1]
Distance2.51 ± 0.08 Mly (769 ± 25 kpc)[2]
Apparent magnitude (V)14.2[1]
Characteristics
TypedIrr/dSph[1]
Apparent size (V)2′ × 2′[1]
Other designations
Pisces I, Psc I, LGS 3,[1] PGC 3792,[1] LEDA 3792

The Pisces Dwarf, also known as Pisces I (Psc I) or LGS3,[1] is an irregular dwarf galaxy and suspected satellite galaxy of the Triangulum Galaxy (M33), located within the Pisces constellation.[2][3] Discovered by astronomer Valentina Karachentseva in 1976,[3] it is approaching the Milky Way at 287 km/s, evident by its blueshift, and may be a galaxy currently transitioning between a dwarf spheroidal and dwarf irregular galaxy;[4] alternatively, it may be a rare unique version of one of the two types.[2]

Structure

The Pisces Dwarf has a very irregular shape, and is composed primarily of moderately aged and young stars, as given by its metallicity of [Fe/H]=−2.10 ± 0.22.[2] Its star formation has declined, with its peak starburst period suspected to be an estimated 8 billion years ago,[5] and a significant lack of new star formation within the past 100 million years.[2][6] It is suspected to be a potential transition galaxy, currently transitioning from a dwarf irregular to a dwarf spheroidal galaxy.[3][6][7]

  • The Pisces Dwarf in combined UV and visible light
    The Pisces Dwarf in combined UV and visible light
  • Cropped Hubble image of part of Pisces I
    Cropped Hubble image of part of Pisces I

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 "NASA/IPAC Extragalactic Database". Results for Pisces Dwarf. http://nedwww.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=Pisces+Dwarf#ObjNo1. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 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:10.1111/j.1365-2966.2004.08514.x. Bibcode: 2005MNRAS.356..979M. 
  3. ↑ 3.0 3.1 3.2 "Dwarf Galaxies in Pisces - NASA Science" (in en-US). 2016-08-11. https://science.nasa.gov/asset/hubble/dwarf-galaxies-in-pisces/. 
  4. ↑ Garofalo, Alessia; Tantalo, Maria; Cusano, Felice; Clementini, Gisella; Calura, Francesco; Muraveva, Tatiana; Paris, Diego; Speziali, Roberto (2021-07-01). "Born in a Pair (?): Pisces II and Pegasus III*". The Astrophysical Journal 916 (1): 10. doi:10.3847/1538-4357/ac0253. ISSN 0004-637X. Bibcode: 2021ApJ...916...10G. 
  5. ↑ Karachentseva, V. E. (1976). "Some characteristics of isolated pairs composed of a normal galaxy and DDO-dwarf". Soobshch. Spets. Astrofiz. Obs. 18 (18): 42–51. Bibcode: 1976SoSAO..18...42K. https://books.google.com/books?id=A20hAAAAMAAJ&q=%D0%BA%D0%B0%D1%80%D0%B0%D1%87%D0%B5%D0%BD%D1%86%D0%B5%D0%B2%D0%B0+%22%D1%85%D0%B0%D1%80%D0%B0%D0%BA%D1%82%D0%B5%D1%80%D0%B8%D1%81%D1%82%D0%B8%D0%BA%D0%B8+%D0%B8%D0%B7%D0%BE%D0%BB%D0%B8%D1%80%D0%BE%D0%B2%D0%B0%D0%BD%D0%BD%D1%8B%D1%85%22. 
  6. ↑ 6.0 6.1 Miller, B. W., Dolphin, A. E., Lee, M. G., Kim, S. C., Hodge, P. (2001). "The Star Formation History of LGS3". The Astrophysical Journal 562 (2): 713–726. doi:10.1086/323853. Bibcode: 2001ApJ...562..713M. 
  7. ↑ Hidalgo, Sebastian L.; Aparicio, Antonio; Skillman, Evan; Monelli, Matteo; Gallart, Carme; Cole, Andrew; Dolphin, Andrew; Weisz, Daniel et al. (2011). "The Acs Lcid Project. V. The Star Formation History of the Dwarf Galaxy Lgs-3: Clues to Cosmic Reionization and Feedback". The Astrophysical Journal 730 (1): 14. doi:10.1088/0004-637X/730/1/14. Bibcode: 2011ApJ...730...14H. 

Coordinates: Sky map 01h 03m 55.0s, +21° 53′ 06″



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