120347 Salacia

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120347 Salacia
Discovered by Henry G. Roe, Michael E. Brown, Kristina M. Barkume
Discovery date September 22, 2004
MPC designation (120347) 2004 SB60
Pronunciation /sæˈlʃiə/ or /səˈlʃə/[3]
Minor planet category Cubewano (MPC)[1]
Extended (DES)[2]
Orbital characteristics[4]
Aphelion 46.5395 AU
Perihelion 37.8383 AU
Semi-major axis 42.1889 AU
Eccentricity 0.10312
Orbital period 274.03 yr (100091 d)
Mean anomaly 113.75°
Inclination 23.9396°
Longitude of ascending node 280.1885°
Argument of perihelion 311.078°
Known satellites Actaea
(286±24 km)
Physical characteristics
Dimensions 854±45 km[5]
905±103 km[6]
Mass 4.5×1020 kg[6]
4.66×1020 kg (system mass)[6]
Mean density 1.16+0.59
Sidereal rotation period 6.09 h[4]
Albedo 0.035+0.010
Absolute magnitude (H) 4.2[4]

120347 Salacia[7] is a large planetoid of the Kuiper belt. It was discovered on September 22, 2004, by Henry G. Roe, Michael E. Brown, and Kristina M. Barkume at the Palomar Observatory. It is probably a dwarf planet.[8] Salacia's diameter is estimated to be 850 km due to a low albedo.

It has been observed 100 times with precovery images back to 1982.[4]

Salacia orbits the Sun at an average distance slightly greater than that of Pluto.


(120347) 2004 SB60 was assigned the name Salacia /sæˈlʃə/ on 18 February 2011. Salacia is the goddess of salt water and the wife of Neptune.[9]

The moon's name Actaea /ækˈtə/ was assigned on the same date. Actaea is a nereid, or sea nymph.

Physical properties[edit]

Even though Salacia has an inclination of 24°, it is not a member of the Haumea family since the near infrared spectrum is basically featureless and shows less than 5% water ice.[10] The total mass of the Salacia–Actaea system is (4.66±0.22)×1020 kg. From the relative diameters about 96% of this mass should be in Salacia itself. Salacia has the lowest albedo and density known of any TNO that big.[6]

Mike Brown's website lists Salacia as "highly likely" to be a dwarf planet,[8] but the IAU has not formally recognized it as such.[11][12]


Salacia has one natural satellite, Actaea, that orbits its primary every 5.494 days at a distance of 5619±87 km and with an eccentricity of e= 0.0084±0.0076.[6] It has a diameter of 286±24 km[5] to 303±35 km.[6] It was discovered on 21 July 2006 by Keith S. Noll, Harold Levison, Denise Stephens and Will Grundy with the Hubble Space Telescope.[13]


  1. ^ "MPEC 2009-R09 :Distant Minor Planets (2009 SEPT. 16.0 TT)". IAU Minor Planet Center. 2009-09-04. Retrieved 2011-07-05. 
  2. ^ Marc W. Buie (2007-08-12 using 62 of 73 observations). "Orbit Fit and Astrometric record for 120347". SwRI (Space Science Department). Retrieved 2009-10-04. 
  3. ^ sal-AY-shee-ə, sə-LAY-shə
  4. ^ a b c d "JPL Small-Body Database Browser: 120347 (2004 SB60)". 2010-11-05 last obs. Retrieved 2012-05-07. 
  5. ^ a b S. Fornasier, E. Lellouch, T. Müller, P. Santos-Sanz, P. Panuzzo, C. Kiss, T. Lim, M. Mommert, D. Bockelée-Morvan, E. Vilenius, J. Stansberry, G.P. Tozzi, S. Mottola, A. Delsanti, J. Crovisier, R. Duffard, F. Henry, P. Lacerda, A. Barucci, & A. Gicquel (2013). TNOs are Cool: A survey of the trans-Neptunian region. VIII. Combined Herschel PACS and SPIRE observations of 9 bright targets at 70–500 µm.
  6. ^ a b c d e f g h J.A. Stansberry (2012). "Physical Properties of Trans-Neptunian Binaries (120347) Salacia–Actaea and (42355) Typhon–Echidna". Elsevier. Retrieved 2012-04-27. 
  7. ^ MPC 73984
  8. ^ a b Michael E. Brown. "How many dwarf planets are there in the outer solar system? (updates daily)". California Institute of Technology. Retrieved 2011-08-25. 
  9. ^ johnstonsarchive.net
  10. ^ E.L. Schaller and M.E. Brown (2008). "Detection of Additional Members of the 2003 EL61 Collisional Family via Near-Infrared Spectroscopy". Astrophysical Journal. arXiv:0808.0185. Bibcode:2008ApJ...684L.107S. doi:10.1086/592232. 
  11. ^ "Planetary Names: Planet and Satellite Names and Discoverers". Gazetteer of Planetary Nomenclature. International Astronomical Union (Working Group for Planetary System Nomenclature). Retrieved 10 June 2012. 
  12. ^ NASA. "List of Dwarf Planets". Retrieved 2012-06-09. 
  13. ^ [1]

External links[edit]