(208996) 2003 AZ84

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(208996) 2003 AZ84
Discovered by C. Trujillo
M. Brown
Discovery date 13 January 2003
MPC designation (208996) 2003 AZ84
Orbital characteristics[1][3]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 3
Observation arc 7289 days (19.96 yr)
Aphelion 46.645 AU (6.9780 Tm)
Perihelion 32.632 AU (4.8817 Tm)
39.638 AU (5.9298 Tm)
Eccentricity 0.17676
249.56 yr (91152.7 d)
0° 0m 14.218s / day
Inclination 13.569°
Known satellites 1 (68 km)?[5]
Earth MOID 31.6161 AU (4.72970 Tm)
Jupiter MOID 27.3461 AU (4.09092 Tm)
Jupiter Tisserand parameter 5.413
Physical characteristics
Dimensions 727.0+61.9
13.42 h (0.559 d)
6.75±0.04 hr[8]
Temperature ≈44 K
B−V= 0.67±0.05;
V−R= 0.38±0.04[7]
20.2 (opposition)[10]
3.74±0.08,[7] 3.8[1]

(208996) 2003 AZ84, also written as 2003 AZ84, is a plutino, like Pluto, in a 2:3 resonance with Neptune.[3][4] Its light-curve amplitude deviates little from that of an ellipsoid, which suggests that it is likely one with small albedo spots.[11] Tancredi (2010) considers (208996) 2003 AZ84 to very probably be a dwarf planet,[12] although the International Astronomical Union does not currently classify it as such. It was discovered on January 13, 2003 by C. Trujillo and M. Brown[1] using the Samuel Oschin telescope in the Palomar Observatory.

Orbit and rotation[edit]

(208996) 2003 AZ84 is a plutino, which means that it is in a 2:3 orbital resonance with Neptune, similar to that of Pluto.[4] It orbits the Sun in just over 247 Earth years.

The orbit of plutino (208996) 2003 AZ84 compared to Pluto and Neptune
Contemporary Orbits of the Trans Neptunian Object 2003 AZ84

(208996) 2003 AZ84 is currently 45.3 AU from the Sun[10] and came to aphelion (farthest distance from the Sun) in 1982.[13] It will come to perihelion in 2107.[1] Simulations by the Deep Ecliptic Survey (DES) show that over the next 10 million years (208996) 2003 AZ84 will not come closer (qmin) than 31.6 AU from the Sun (it will stay farther away than Neptune).[3]

The rotation period of (208996) 2003 AZ84 is 6.75±0.04 h.[8] (208996) 2003 AZ84 has a lightcurve amplitude of 0.14±0.03.[7]

Physical characteristics[edit]

The Spitzer Space Telescope has estimated its size at 686±96 km,[9] while an analysis of a combination of Spitzer and Hershel data yielded a slightly higher estimate of 727.0+61.9
.[7] These results are in agreement with each other.[note 1] Its large size (208996) 2003 AZ84 makes it a probable dwarf planet. Its mass is unknown since the satellite has not been recovered.[6]

A stellar occultation in 2010 measured a single chord of 573±21 km.[15] But this is only a lower limit for the diameter of (208996) 2003 AZ84 because the chord may not have passed through the center of the body.

The spectra and colors of (208996) 2003 AZ84 are very similar to those of Orcus, another large object in 2:3 resonance with Neptune. Both bodies have a flat featureless spectrum in the visible and moderately strong water ice absorption bands in the near-infrared, although (208996) 2003 AZ84 has a lower albedo. Both bodies also have a weak absorption band near 2.3 μm, which may be caused by ammonia hydrate or methane ice.[16]


Using observations with the Hubble Space Telescope, the discovery of a satellite of (208996) 2003 AZ84 was reported in IAUC 8812 on 22 February 2007.[5][17][18] The object was measured with a separation of 0.22 arcsec and an apparent magnitude difference of 5.0.[17] As of 2012, attempts to recover the satellite have failed.[6] The unrecovered satellite is estimated to be about 68±20 km in diameter.[5]


  1. ^ The results of the previous observation of (208996) 2003 AZ84 by the Herschel were reported in 2010. They were obtained using chop/nod technique yielding 910±60 km.[14] The difference can be explained by the large light-curve amplitude of (208996) 2003 AZ84 and the fact that in 2010 the radiation from it was measured at one particular time, while 2012 determination was based on the time-averaged data.[7]


  1. ^ a b c d e "JPL Small-Body Database Browser: (2003 AZ84)" (2006-02-25 last obs). Retrieved 7 April 2016. 
  2. ^ Marsden, Brian G. (2003-01-26). "MPEC 2003-B27 : 2003 AZ84". IAU Minor Planet Center. Harvard-Smithsonian Center for Astrophysics. Retrieved 2010-01-06. 
  3. ^ a b c d Marc W. Buie (2009-02-18). "Orbit Fit and Astrometric record for 208996". SwRI (Space Science Department). Retrieved 2009-08-29. 
  4. ^ a b c "MPEC 2009-P26 :Distant Minor Planets (2009 August 17.0 TT)". IAU Minor Planet Center. 2009-08-07. Retrieved 2009-08-28. 
  5. ^ a b c Wm. Robert Johnston (9 April 2009). "2003 AZ84". Johnston's Archive. Retrieved 2012-02-03. 
  6. ^ a b c Plutokiller (2012-02-03). "After a bit more than 3 hrs on 2003AZ84 still no obvious moon.". Twitter. Retrieved 2012-02-03. 
  7. ^ a b c d e f g Mommert, Michael; Harris, A. W.; Kiss, C.; Pál, A.; Santos-Sanz, P.; Stansberry, J.; Delsanti, A.; Vilenius, E.; Müller, T. G.; Peixinho, N.; Lellouch, E.; Szalai, N.; Henry, F.; Duffard, R.; Fornasier, S.; Hartogh, P.; Mueller, M.; Ortiz, J. L.; Protopapa, S.; Rengel, M.; Thirouin, A. (May 2012). "TNOs are cool: A survey of the trans-Neptunian region—V. Physical characterization of 18 Plutinos using Herschel-PACS observations". Astronomy & Astrophysics. 541: A93. arXiv:1202.3657free to read. Bibcode:2012A&A...541A..93M. doi:10.1051/0004-6361/201118562. 
  8. ^ a b Thirouin, A.; Ortiz, J. L.; Duffard, R.; Santos-Sanz, P.; Aceituno, F. J.; Morales, N. (2010). "Short-term variability of a sample of 29 trans-Neptunian objects and Centaurs". Astronomy & Astrophysics. 522: A93. arXiv:1004.4841free to read. Bibcode:2010A&A...522A..93T. doi:10.1051/0004-6361/200912340. 
  9. ^ a b John Stansberry; Will Grundy; Mike Brown; Dale Cruikshank; John Spencer; David Trilling; et al. (2008). "Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope". In M. Antonietta Barucci; Hermann Boehnhardt; Dale P. Cruikshank. The Solar System Beyond Neptune (pdf). University of Arizona press. pp. 161–179. arXiv:astro-ph/0702538free to read. ISBN 0-8165-2755-5. 
  10. ^ a b "AstDys (208996) 2003AZ84 Ephemerides". Department of Mathematics, University of Pisa, Italy. Retrieved 2011-01-02. 
  11. ^ Tancredi, G., & Favre, S. (2008) Which are the dwarfs in the Solar System?. Depto. Astronomía, Fac. Ciencias, Montevideo, Uruguay; Observatorio Astronómico Los Molinos, MEC, Uruguay. Retrieved 10-08-2011
  12. ^ Tancredi, G. (2010). "Physical and dynamical characteristics of icy "dwarf planets" (plutoids)". Icy Bodies of the Solar System: Proceedings IAU Symposium No. 263, 2009. 
  13. ^ "HORIZONS Web-Interface". JPL Solar System Dynamics. Retrieved 2009-03-30. 
  14. ^ Muller, T.G.; Lellouch, E.; Stansberry, J.; et al. (2010). ""TNOs are Cool": A survey of the trans-Neptunian region I. Results from the Herschel science demonstration phase (SDP)". Astronomy and Astrophysics. 518: L146. arXiv:1005.2923free to read. Bibcode:2010A&A...518L.146M. doi:10.1051/0004-6361/201014683. 
  15. ^ Braga-Ribas, F.; et al. (2011). "Stellar Occultations by TNOs: the January 08, 2011 by (208996) 2003 AZ84 and the May 04, 2011 by (50000) Quaoar" (pdf). EPSC Abstracts. 6: EPSC-DPS2011-1060–1. 
  16. ^ A. Delsanti; F. Merlin; A. Guilbert–Lepoutre at al. (2010). "Methane, ammonia, and their irradiation products at the surface of an intermediate-size KBO? A portrait of Plutino (90482) Orcus". Astronomy and Astrophysics. 627 (2): 1057. arXiv:1006.4962free to read. Bibcode:2010A&A...520A..40D. doi:10.1051/0004-6361/201014296. 
  17. ^ a b Daniel W. E. Green (2007-02-22). "IAUC 8812: Sats of 2003 AZ_84, (50000), (55637), (90482)". International Astronomical Union Circular. Retrieved 2009-03-26. 
  18. ^ Joel Parker (2007-03-15). "Distant EKO's". The Kuiper Belt Electronic Newsletter. Retrieved 2007-02-25. 

External links[edit]