(208996) 2003 AZ84

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(208996) 2003 AZ84
Discovery[1][2]
Discovered by C. Trujillo
M. Brown
(644)
Discovery date January 13, 2003
Designations
MPC designation (208996) 2003 AZ84
Plutino[3][4]
Orbital characteristics[1][3]
Epoch July 23, 2010 (JD 2455400.5)
Aphelion 46.477 AU (6.9529 Tm)
Perihelion 32.334 AU (4.8371 Tm)
39.406 AU (5.8950 Tm)
Eccentricity 0.179
247.37 a (90352 d)
218.919°
Inclination 13.563°
252.016°
15.874°
Known satellites 1 (68 km)?[5]
(unrecovered)[6]
Physical characteristics
Dimensions 727.0+61.9
−66.5
 km
[7]
6.75±0.04 hr[8]
Albedo 0.09–0.16[9]
0.107+0.023
−0.016
[7]
Temperature ≈44 K
Spectral type
B−V= 0.67±0.05;
V−R= 0.38±0.04[7]
20.2 (opposition)[10]
3.74±0.08[7]

(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

(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

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
−66.5
 km
.[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]

Satellite

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]

Notes

  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]

References

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  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
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External links