(208996) 2003 AZ84
|Discovered by||C. Trujillo,
|Discovery date||January 13, 2003|
|MPC designation||(208996) 2003 AZ84|
|Minor planet category||Plutino|
|Epoch July 23, 2010 (JD 2455400.5)|
|Aphelion||46.477 AU (6.9529 Tm)|
|Perihelion||32.334 AU (4.8371 Tm)|
|Semi-major axis||39.406 AU (5.8950 Tm)|
|Orbital period||247.37 a (90352 d)|
|Longitude of ascending node||252.016°|
|Argument of perihelion||15.874°|
|Known satellites||1 (68 km)?
>573±21 km (chord)
|Sidereal rotation period||6.75±0.04 hr|
|Spectral type||B−V= 0.67±0.05;
|Apparent magnitude||20.2 (opposition)|
|Absolute magnitude (H)||3.74±0.08|
(208996) 2003 AZ84, also written as 2003 AZ84, is a plutino, like Pluto, in a 2:3 resonance with Neptune. Light-curve-amplitude analysis shows only small deviations, which suggests that it is likely a spheroid with small albedo spots. Tancredi (2010) consider 2003 AZ84 to very probably be a dwarf planet, 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 using the Samuel Oschin telescope in the Palomar Observatory.
Orbit and rotation
2003 AZ84 is currently 45.3 AU from the Sun and came to aphelion (farthest distance from the Sun) in 1982. It will come to perihelion in 2107. Simulations by the Deep Ecliptic Survey (DES) show that over the next 10 million years 2003 AZ84 will not come closer (qmin) than 31.6 AU from the Sun (it will stay farther away than Neptune).
The Spitzer Space Telescope has estimated its size at 686±96 km, while an analysis of a combination of Spitzer and Hershel data yielded a slightly higher estimate of 727.0+61.9
−66.5 km. These results are in agreement with each other.[note 1] Its large size 2003 AZ84 makes it a probable dwarf planet. Its mass is unknown since the satellite has not been recovered.
A stellar occultation in 2010 measured a single chord of 573±21 km. But this is only a lower limit for the diameter of 2003 AZ84 because the chord may not have passed through the center of the body.
The spectra and colors of 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 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.
Using observations with the Hubble Space Telescope, the discovery of a satellite of 2003 AZ84 was reported in IAUC 8812 on 22 February 2007. The object was measured with a separation of 0.22 arcsec and an apparent magnitude difference of 5.0. As of 2012[update], attempts to recover the satellite have failed. The unrecovered satellite is estimated to be about 68±20 km in diameter.
- The results of the previous observation of 2003 AZ84 by the Herschel were reported in 2010. They were obtained using chop/nod technique yielding 910±60 km. The difference can be explained by the large light-curve amplitude of 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.
- "JPL Small-Body Database Browser: (2003 AZ84)". 2006-02-25 last obs. Retrieved 2008-07-23.
- Marsden, Brian G. (2003-01-26). "MPEC 2003-B27 : 2003 AZ84". IAU Minor Planet Center. Harvard-Smithsonian Center for Astrophysics. Retrieved 2010-01-06.
- Marc W. Buie (2009-02-18). "Orbit Fit and Astrometric record for 208996". SwRI (Space Science Department). Retrieved 2009-08-29.
- "MPEC 2009-P26 :Distant Minor Planets (2009 August 17.0 TT)". IAU Minor Planet Center. 2009-08-07. Retrieved 2009-08-28.
- Wm. Robert Johnston (9 April 2009). "2003 AZ84". Johnston's Archive. Retrieved 2012-02-03.
- Plutokiller (2012-02-03). "After a bit more than 3 hrs on 2003AZ84 still no obvious moon.". Twitter. Retrieved 2012-02-03.
- 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:1202.3657. Bibcode:2012A&A...541A..93M. doi:10.1051/0004-6361/201118562.
- John Stansberry, Will Grundy, Mike Brown, Dale Cruikshank, John Spencer, David Trilling, Jean-Luc Margot (2008). "Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope" (pdf). In M. Antonietta Barucci, Hermann Boehnhardt, Dale P. Cruikshank. The Solar System Beyond Neptune. University of Arizona press. pp. 161–179. arXiv:astro-ph/0702538. ISBN 0-8165-2755-5.
- 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.
- 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:1004.4841. Bibcode:2010A&A...522A..93T. doi:10.1051/0004-6361/200912340.
- "AstDys (208996) 2003AZ84 Ephemerides". Department of Mathematics, University of Pisa, Italy. Retrieved 2011-01-02.
- 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
- Tancredi, G. (2010). "Physical and dynamical characteristics of icy "dwarf planets" (plutoids)". Icy Bodies of the Solar System: Proceedings IAU Symposium No. 263, 2009.
- "HORIZONS Web-Interface". JPL Solar System Dynamics. Retrieved 2009-03-30.
- 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:1005.2923. Bibcode:2010A&A...518L.146M. doi:10.1051/0004-6361/201014683.
- 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:1006.4962. Bibcode:2010A&A...520A..40D. doi:10.1051/0004-6361/201014296.
- 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.
- Joel Parker (2007-03-15). "Distant EKO's". The Kuiper Belt Electronic Newsletter. Retrieved 2007-02-25.