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Palomar 12

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Title: Palomar 12  
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Subject: Sagittarius Dwarf Spheroidal Galaxy, Local Group, Robert G. Harrington, Today's featured article/September 23, 2006, Globular cluster
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Palomar 12

Palomar 12
Palomar 12 by Hubble Space Telescope, 3.36′ view
Observation data (J2000 epoch)
Class XII
Constellation Capricornus
Right ascension 21h 46m 38.84s[1]
Declination –21° 15′ 09.4″[1]
Distance 63.6 ± 2.9 kly (19.50 ± 0.89 kpc)[2]
Apparent magnitude (V) 11.99
Apparent dimensions (V) 17′.4
Physical characteristics
Mass 1.59×104[3] M
Radius 162 ± 8 ly[4]
Metallicity –0.85[3] dex
Estimated age 6.5 Gyr[5]
Other designations GCl 123[6]

Palomar 12 is a globular cluster in the constellation Capricornus that belongs to the halo of the Milky Way Galaxy.

First discovered on the National Geographic Society – Palomar Observatory Sky Survey plates by Robert G. Harrington and Fritz Zwicky,[7] it was catalogued as a globular cluster. However Zwicky came to believe this was actually a nearby dwarf galaxy in the Local Group. It is a relatively young cluster, being about 30% younger than most of the globular clusters in the Milky Way.[2] It is metal-rich with a metallicity of [Fe/H] ~= -0.8.[5] It has an average luminosity distribution of Mv = -4.48.[8]

Based on proper motion studies, this cluster was first suspected in 2000 to have been captured from the Sagittarius dwarf galaxy about 1.7 Ga ago.[9] It is now generally believed to be a member of the Sagittarius dwarf galaxy (Cohen 2004, Sbordone et al. 2006).[5] It is estimated to be 6.5 Gyr old.[5]


  1. ^ a b
  2. ^ a b
  3. ^ a b
  4. ^ distance × sin( diameter_angle / 2 ) = 162 ly. radius
  5. ^ a b c d
  6. ^
  7. ^
  8. ^
  9. ^

External links

  • Simbad reference data
  • SEDS: Palomar 12, Capricornus Dwarf
  • Palomar 12 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images

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