(208996) 2003 AZ84

(208996) 2003 AZ84
Orbit of Pluto, 2003 AZ84 and Neptune
Discovery [1][2]
Discovered by C. Trujillo
M. E. Brown
Discovery site NEAT–Palomar Obs.
Discovery date 13 January 2003
Designations
MPC designation (208996) 2003 AZ84
2003 AZ84
TNO [1] · plutino[3][4][5] · distant [6]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 3
Observation arc 20.96 yr (7,654 days)
Earliest precovery date 19 March 1996
Aphelion 46.627 AU
Perihelion 32.392 AU
39.510 AU
Eccentricity 0.1801
248.35 yr (90,710 days)
231.33°
0° 0m 14.4s / day
Inclination 13.588°
252.16°
14.225°
Known satellites 1[7] (diameter: 72 km)[4][8]
(unrecovered)[9]
Physical characteristics
Dimensions 940 × 766 × 490 km[10]
Mean diameter
 573±21 km (or larger)[11]
686±96 km[12]
727±67 km[13]
723±64 km (derived)[8]
737.06 km (derived)[14]
747 km[15]
772 km[4]
6.71±0.05 h[16]
6.76±0.02 h[17]
6.79±0.05 h[18]
13.42 h[14]
0.097[4]
0.09–0.16[12]
0.10 (assumed)[14]
0.107±0.023[13]
0.11 (radiometric)[15]
BB [19][20] · C [14]
B–V = 0.67±0.05[13]
V–R = 0.38±0.04[13]
20.2 (opposition)[21]
3.537±0.053 (R)[22]
3.54±0.03[23] · 3.7[1][15]
3.74±0.08[13]
3.77±0.04[19]
3.775±0.019[24]
3.78±0.06[14][25]

    (208996) 2003 AZ84 is a trans-Neptunian object, possibly binary,[7][9] from the outer regions of the Solar System, approximately 700 kilometers in diameter. It belongs to the plutinos – a group of minor planets named after its largest member Pluto – as it orbits in a 2:3 resonance with Neptune in the Kuiper belt.[3][5] It was discovered on 13 January 2003, by American astronomers Chad Trujillo and Michael Brown during the NEAT survey using the Samuel Oschin telescope at Palomar Observatory.[6]

    Its lightcurve amplitude deviates little from that of an ellipsoid, which suggests that it is likely one with small albedo spots.[26]

    Considered a very likely dwarf planet by astronomers Gonzalo Tancredi and Michael Brown, it is currently not recognized as such by the IAU.[27][15]

    Orbit and rotation

    2003 AZ84 is a plutino, which means that it is in a 2:3 orbital resonance with Neptune, similar to that of Pluto.[5] It orbits the Sun in just over 247 Earth years. It is currently 45.3 AU from the Sun[21] and came to aphelion (farthest distance from the Sun) in 1982.[28] It will come to perihelion in 2107.[1] 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).[3]

    Two rotational lightcurves of this minor planet were obtained by Scott Sheppard and José Ortiz in 2003 and 2006. Lightcurve analysis gave an ambiguous rotation period of 6.71 and 6.76 hours with a brightness variation of 0.14 and 0.10 in magnitude, respectively (U=2/2-).[16][17]

    Physical characteristics

    The Spitzer Space Telescope has estimated its size at 686±96 km,[12] while an analysis of a combination of Spitzer and Hershel data yielded a slightly higher estimate of 727.0+61.9
    −66.5     km    .[13] 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.[9]

    A stellar occultation in 2010 measured a single chord of 573±21 km.[30] 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.[31]

    Satellite

    Using observations with the Hubble Space Telescope, the discovery of a satellite of 2003 AZ84 was reported in IAUC 8812 on 22 February 2007.[8][7][32] The object was measured with a separation of 0.22 arcsec and an apparent magnitude difference of 5.0.[7] As of 2012, attempts to recover the satellite have failed.[9] The unrecovered satellite is estimated to be about 72±12 km in diameter.[4][8]

    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.[29] 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.[13]

    References

    1. 1 2 3 4 5 "JPL Small-Body Database Browser: 208996 (2003 AZ84)" (2016-03-03 last obs.). Jet Propulsion Laboratory. Retrieved 9 February 2017.
    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. 1 2 3 Marc W. Buie (2009-02-18). "Orbit Fit and Astrometric record for 208996". SwRI (Space Science Department). Retrieved 2009-08-29.
    4. 1 2 3 4 5 Johnston, Wm. Robert (30 December 2017). "List of Known Trans-Neptunian Objects". Johnston's Archive. Retrieved 16 January 2018.
    5. 1 2 3 "MPEC 2009-P26 :Distant Minor Planets (2009 August 17.0 TT)". IAU Minor Planet Center. 2009-08-07. Retrieved 2009-08-28.
    6. 1 2 "208996 (2003 AZ84)". Minor Planet Center. Retrieved 9 February 2017.
    7. 1 2 3 4 Brown, M. E.; Suer, T.-A. (February 2007). "Satellites of 2003 AZ_84, (50000), (55637), and (90482)". IAU Circ. (8812). Bibcode:2007IAUC.8812....1B. Retrieved 9 February 2017.
    8. 1 2 3 4 Wm. Robert Johnston (20 September 2014). "(208996) 2003 AZ84". Johnston's Archive. Retrieved 16 January 2018.
    9. 1 2 3 4 Plutokiller (2012-02-03). "After a bit more than 3 hrs on 2003AZ84 still no obvious moon". Twitter. Retrieved 2012-02-03.
    10. ↑ Dias-Oliveira, A.; Sicardy, B.; Ortiz, J. L.; Braga-Ribas, F.; Leiva, R.; Vieira-Martins, R.; et al. (July 2017). "Study of the Plutino Object (208996) 2003 AZ84 from Stellar Occultations: Size, Shape, and Topographic Features" (PDF). The Astronomical Journal. 154 (1): 13. arXiv:1705.10895. Bibcode:2017AJ....154...22D. doi:10.3847/1538-3881/aa74e9. Retrieved 16 January 2018.
    11. ↑ Braga-Ribas, F.; Sicardy, B.; Colas, F.; Lecacheux, J.; Maury, A.; Ortiz, J. L.; et al. (March 2011). "Stellar Occultation by Transneptunian Object (208996) 2003 AZ84". Central Bureau Electronic Telegrams (2675). Bibcode:2011CBET.2675....1B. Retrieved 9 February 2017.
    12. 1 2 3 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/0702538. Bibcode:2008ssbn.book..161S. ISBN 0-8165-2755-5.
    13. 1 2 3 4 5 6 7 Mommert, M.; Harris, A. W.; Kiss, C.; Pál, A.; Santos-Sanz, P.; Stansberry, J.; et al. (May 2012). "TNOs are cool: A survey of the trans-Neptunian region. V. Physical characterization of 18 Plutinos using Herschel-PACS observations". Astronomy and Astrophysics. 541: 17. arXiv:1202.3657. Bibcode:2012A&A...541A..93M. doi:10.1051/0004-6361/201118562. Retrieved 9 February 2017.
    14. 1 2 3 4 5 "LCDB Data for (208996)". Asteroid Lightcurve Database (LCDB). Retrieved 9 February 2017.
    15. 1 2 3 4 Michael E. Brown. "How many dwarf planets are there in the outer solar system?". California Institute of Technology. Retrieved 16 January 2018.
    16. 1 2 Sheppard, Scott S.; Jewitt, David C. (June 2003). "Hawaii Kuiper Belt Variability Project: An Update". Earth (1): 207–219. Bibcode:2003EM&P...92..207S. doi:10.1023/B:MOON.0000031943.12968.46. Retrieved 9 February 2017.
    17. 1 2 Ortiz, J. L.; Gutiérrez, P. J.; Santos-Sanz, P.; Casanova, V.; Sota, A. (March 2006). "Short-term rotational variability of eight KBOs from Sierra Nevada Observatory". Astronomy and Astrophysics. 447 (3): 1131–1144. Bibcode:2006A&A...447.1131O. doi:10.1051/0004-6361:20053572. Retrieved 9 February 2017.
    18. ↑ Thirouin, A.; Ortiz, J. L.; Duffard, R.; Santos-Sanz, P.; Aceituno, F. J.; Morales, N. (November 2010). "Short-term variability of a sample of 29 trans-Neptunian objects and Centaurs". Astronomy and Astrophysics. 522: 43. arXiv:1004.4841. Bibcode:2010A&A...522A..93T. doi:10.1051/0004-6361/200912340. Retrieved 9 February 2017.
    19. 1 2 Perna, D.; Barucci, M. A.; Fornasier, S.; DeMeo, F. E.; Alvarez-Candal, A.; Merlin, F.; et al. (February 2010). "Colors and taxonomy of Centaurs and trans-Neptunian objects". Astronomy and Astrophysics. 510. arXiv:0912.2621. Bibcode:2010A&A...510A..53P. doi:10.1051/0004-6361/200913654. Retrieved 9 February 2017.
    20. ↑ Belskaya, Irina N.; Barucci, Maria A.; Fulchignoni, Marcello; Dovgopol, Anatolij N. (April 2015). "Updated taxonomy of trans-neptunian objects and centaurs: Influence of albedo". Icarus. 250: 482–491. Bibcode:2015Icar..250..482B. doi:10.1016/j.icarus.2014.12.004. Retrieved 9 February 2017.
    21. 1 2 "AstDys (208996) 2003AZ84 Ephemerides". Department of Mathematics, University of Pisa, Italy. Retrieved 2011-01-02.
    22. ↑ Peixinho, N.; Delsanti, A.; Guilbert-Lepoutre, A.; Gafeira, R.; Lacerda, P. (October 2012). "The bimodal colors of Centaurs and small Kuiper belt objects". Astronomy and Astrophysics. 546: 12. arXiv:1206.3153. Bibcode:2012A&A...546A..86P. doi:10.1051/0004-6361/201219057. Retrieved 9 February 2017.
    23. ↑ Boehnhardt, H.; Schulz, D.; Protopapa, S.; Gö; tz, C. (November 2014). "Photometry of Transneptunian Objects for the Herschel Key Program `TNOs are Cool'". Earth. 114 (1–2): 35–57. Bibcode:2014EM&P..114...35B. doi:10.1007/s11038-014-9450-x. Retrieved 9 February 2017.
    24. ↑ Rabinowitz, David L.; Schaefer, Bradley E.; Schaefer, Martha; Tourtellotte, Suzanne W. (October 2008). "The Youthful Appearance of the 2003 EL61 Collisional Family". The Astronomical Journal. 136 (4): 1502–1509. arXiv:0804.2864. Bibcode:2008AJ....136.1502R. doi:10.1088/0004-6256/136/4/1502. Retrieved 9 February 2017.
    25. ↑ Santos-Sanz, P.; Ortiz, J. L.; Barrera, L.; Boehnhardt, H. (February 2009). "New BVRI photometry results on Kuiper Belt Objects from the ESO VLT". Astronomy and Astrophysics. 494 (2): 693–706. arXiv:0812.4525. Bibcode:2009A&A...494..693S. doi:10.1051/0004-6361:20078301. Retrieved 9 February 2017.
    26. ↑ 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
    27. ↑ Tancredi, G. (2010). "Physical and dynamical characteristics of icy "dwarf planets" (plutoids)". Icy Bodies of the Solar System: Proceedings IAU Symposium No. 263, 2009.
    28. ↑ "HORIZONS Web-Interface". JPL Solar System Dynamics. Retrieved 2009-03-30.
    29. ↑ 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.
    30. ↑ 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.
    31. ↑ 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.
    32. ↑ Joel Parker (2007-03-15). "Distant EKO's". The Kuiper Belt Electronic Newsletter. Retrieved 2007-02-25.
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