Pisces I (dwarf galaxy)

Not to be confused with Iota Piscium or PSCI.

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Pisces I Dwarf Galaxy

Observation data (J2000 epoch)
Constellation| Pisces
Right ascension| 01h 03m 56.6s[1]
Declination| +21° 53′ 41″[1]
Distance| 260 kly (80 kpc)[2]
Absolute magnitude (V)| −10.35[3]
Characteristics
Type| dIrr/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[edit]

1. ^ a b Karachentsev ID, et al. (2004). "A Catalog of Neighboring Galaxies". Astronomical Journal. 127 (4): 2031–2068. Bibcode:2004AJ....127.2031K. doi:10.1086/382905.
2. ^ a b c d e 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, arXiv:0906.0498, Bibcode:2009MNRAS.398.1757W, doi:10.1111/j.1365-2966.2009.15242.x.
3. ^ a b 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. arXiv:0903.3871. Bibcode:2009ApJ...697.1993B. doi:10.1088/0004-637X/697/2/1993.
4. ^ a b c Kollmeier, Juna A.; et al. (2009), "Spectroscopic Confirmation of the Pisces Overdensity", The Astrophysical Journal Letters, 705 (2): L158–L162, arXiv:0908.1381, Bibcode:2009ApJ...705L.158K, doi:10.1088/0004-637X/705/2/L158.
5. ^ a b "NAME Pisces I". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 23 March 2018.
6. ^ "Object No. 1 - Pisces I". NASA/IPAC Extragalactic Database.
7. ^ a b 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, arXiv:1002.0504, Bibcode:2010ApJ...712L.103B, doi:10.1088/2041-8205/712/1/L103.

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Milky Way

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Milky Way → Milky Way subgroup → Local Group → Local Sheet → Virgo Supercluster → Laniakea Supercluster → KBC Void → Observable universe → Universe
Each arrow (→) may be read as "within" or "part of".

Structure|

| Galactic Center|

* Sagittarius A
* Sagittarius A*
* Supermassive black hole

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Disk|

* Carina–Sagittarius
* Norma–Cygnus
* Orion–Cygnus
* Perseus
* Scutum–Centaurus
* Near 3 kpc Arm
* Far 3 kpc Arm

Halo|

* Aquarius Stream
* Fimbulthul stream
* Gaia Sausage
* Helmi stream
* Magellanic Stream
* Monoceros Ring
* Palomar 5 stream
* Pisces-Eridanus stream
* Sagittarius Stream
* Virgo Stream

Satellite
galaxies|

| Magellanic Clouds|

* Large Magellanic Cloud
* Small Magellanic Cloud
* Magellanic Bridge

|

Dwarfs|

* Antlia 2
* Boötes I
* Boötes II
* Boötes III
* Canes Venatici I
* Canes Venatici II
* Canis Major
* Carina
* Coma Berenices
* Crater 2
* Draco
* Eridanus II
* Fornax
* Hercules
* Leo I
* Leo II
* Leo IV
* Leo V
* Leo T
* Phoenix
* Pisces I
* Pisces II
* Reticulum II
* Sagittarius Spheroidal
* Segue 1
* Segue 2
* Sculptor
* Sextans
* Triangulum II
* Ursa Major I
* Ursa Major II
* Ursa Minor
* Virgo I
* Willman 1

Related|

* Alternate names
* Andromeda–Milky Way collision
* Baade's Window
* In mythology
* Zone of Avoidance

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