Article · Wikipedia archive · Last revised Jul 24, 2026

Pisces Dwarf

The Pisces Dwarf, also known as Pisces I or LGS3, is an irregular dwarf galaxy and suspected satellite galaxy of the Triangulum Galaxy (M33), located within the Pisces constellation. Discovered by astronomer Valentina Karachentseva in 1976, 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; alternatively, it may be a rare unique version of one of the two types.

Last revised
Jul 24, 2026
Read time
≈ 2 min
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Citations
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Wikipedia ↗
Pisces Dwarf
Hubble Space Telescope image of the Pisces Dwarf
Observation data (J2000 epoch)
ConstellationPisces
Right ascension01h 03m 55.0s1
Declination+21° 53′ 06″1
Redshift-287 ± 0 km/s1
Distance2.51 ± 0.08 Mly (769 ± 25 kpc)2
Apparent magnitude (V)14.21
Characteristics
TypedIrr/dSph1
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.23 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.26 It is suspected to be a potential transition galaxy, currently transitioning from a dwarf irregular to a dwarf spheroidal galaxy.367

  • 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

References

  1. "NASA/IPAC Extragalactic Database". Results for Pisces Dwarf. Retrieved 2007-03-15.
  2. 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. arXiv:astro-ph/0410489. Bibcode:2005MNRAS.356..979M. doi:10.1111/j.1365-2966.2004.08514.x.
  3. "Dwarf Galaxies in Pisces - NASA Science". 2016-08-11. Retrieved 2026-04-21.
  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. arXiv:2105.11488. Bibcode:2021ApJ...916...10G. doi:10.3847/1538-4357/ac0253. ISSN 0004-637X.
  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.
  6. 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. arXiv:astro-ph/0108408. Bibcode:2001ApJ...562..713M. doi:10.1086/323853. S2CID 119089499.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. Hidalgo, Sebastian L.; Aparicio, Antonio; Skillman, Evan; Monelli, Matteo; Gallart, Carme; Cole, Andrew; Dolphin, Andrew; Weisz, Daniel; Bernard, Edouard J.; Cassisi, Santi; Mayer, Lucio; Stetson, Peter; Tolstoy, Eline; Ferguson, Henry (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. arXiv:1101.5762. Bibcode:2011ApJ...730...14H. doi:10.1088/0004-637X/730/1/14. S2CID 118411768.
External links