Astronomy:Pisces I (dwarf galaxy)

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Pisces I Dwarf Galaxy
Observation data (J2000 epoch)
ConstellationPisces
Right ascension 01h 03m 56.6s[1]
Declination+21° 53′ 41″[1]
Distance260 kly (80 kpc)[2]
Absolute magnitude (V)−10.35[3]
Characteristics
TypedIrr/dSph[3]
Apparent size (V)~1°[4]
Other designations
Pisces Overdensity,[2] Psc I,[5] PGC 3792,[6] LEDA 3792[5]

Pisces I (Psc I) or Pisces Overdensity is a clump of stars in the Milky Way's halo, which may be a disrupted dwarf spheroidal galaxy.[7] It is situated in the Pisces constellation and was discovered in 2009 by analysis of distribution of RR Lyrae stars in the data obtained by the Sloan Digital Sky Survey's data.[2] The galaxy is located at the distance of about 80 kpc from the Sun and moves towards it with a speed of about 75 km/s.[4]

Pisces I is one of the faintest satellites of the Milky Way.[7] Its mass is estimated to be at least 105 Solar masses.[2] However it has a large size of about several degrees (around 1 kpc) and may be in a transitional phase between a gravitationally bound galaxy and completely unbound system.[4] Pisces I is located near the plane, where the Magellanic Clouds lie. There may exist a connection between the Magellanic stream and this galaxy.[2]

References

  1. ↑ 1.0 1.1 Karachentsev, I. D. et al. (2004). "A Catalog of Neighboring Galaxies". Astronomical Journal 127 (4): 2031–2068. doi:10.1086/382905. Bibcode: 2004AJ....127.2031K. http://www.iop.org/EJ/abstract/1538-3881/127/4/2031. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Watkins, L. L. et al. (2009), "Substructure revealed by RR Lyraes in SDSS Stripe 82", Monthly Notices of the Royal Astronomical Society 398 (4): 1757–70, doi:10.1111/j.1365-2966.2009.15242.x, Bibcode: 2009MNRAS.398.1757W. 
  3. ↑ 3.0 3.1 Boyer, Martha L; Skillman, Evan D; Van Loon, Jacco Th; Gehrz, Robert D; Woodward, Charles E (2009). "Aspitzerstudy of Asymptotic Giant Branch Stars. Iii. Dust Production and Gas Return in Local Group Dwarf Irregular Galaxies". The Astrophysical Journal 697 (2): 1993. doi:10.1088/0004-637X/697/2/1993. Bibcode: 2009ApJ...697.1993B. 
  4. ↑ 4.0 4.1 4.2 Kollmeier, Juna A. et al. (2009), "Spectroscopic Confirmation of the Pisces Overdensity", The Astrophysical Journal Letters 705 (2): L158–L162, doi:10.1088/0004-637X/705/2/L158, Bibcode: 2009ApJ...705L.158K. 
  5. ↑ 5.0 5.1 "NAME Pisces I". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=NAME+Pisces+I. 
  6. ↑ "Object No. 1 - Pisces I". NASA/IPAC Extragalactic Database. https://ned.ipac.caltech.edu/cgi-bin/objsearch?objname=pisces+I&extend=no&hconst=73&omegam=0.27&omegav=0.73&corr_z=1&out_csys=Equatorial&out_equinox=J2000.0&obj_sort=RA+or+Longitude&of=pre_text&zv_breaker=30000.0&list_limit=5&img_stamp=YES. 
  7. ↑ 7.0 7.1 Belokurov, V. et al. (2010), "Big fish, small fish: Two New Ultra-Faint Satellites of the Milky Way", The Astrophysical Journal Letters 712: L103–106, doi:10.1088/2041-8205/712/1/L103, Bibcode: 2010ApJ...712L.103B. 




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