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(55565) 2002 AW197

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(55565) 2002 AW197
Hubble Space Telescope image of 2002 AW197 taken in December 2005
Discovery[1][2]
Discovered byPalomar Obs.[a]
Discovery sitePalomar Obs.
Discovery date10 January 2002
Designations
2002 AW197
TNO[3] · classical (hot)[4]: 56 
distant[1] · Scat-Ext[5]
Orbital characteristics (barycentric)[6][3]
Epoch 25 February 2023 (JD 2460000.5)
Uncertainty parameter 2[1]
Observation arc27.15 yr (9,915 d)
Earliest precovery date29 December 1997
Aphelion53.280 AU
Perihelion41.112 AU
47.196 AU
Eccentricity0.1289
324.02 yr (118,349 d)
299.003°
0° 0m 10.951s / day
Inclination24.382°
297.481°
≈ 5 May 2078[7]
±0.4 days[3]
295.928°
Physical characteristics
768±39 km[8]
8.86±0.01 h[9]: 6 [10]: 1132–1133 
8.78 h[11]: 6 
0.112+0.012
−0.011[8]
IR[12][13] · (moderately red)
B–V = 0.920±0.020[14]
V–R = 0.560±0.020[14]
V–I = 1.170±0.010[13]
20.0[15][1]
3.568±0.046[16]
3.44[3]

(55565) 2002 AW197 (provisional designation 2002 AW197) is a classical, non-resonant trans-Neptunian object from the Kuiper belt in the outermost region of the Solar System, also known as a cubewano. It was discovered on 10 January 2002 by astronomers at Palomar Observatory. With a diameter of about 770 kilometers (500 miles), 2002 AW197 is approximately tied with 2013 FY27 (to within measurement uncertainties) as the largest unnamed object in the Solar System.

2002 AW197 has a rotation period of 8.8 hours and has a moderately red color.[12] The object's brightness does not significantly vary as it rotates, which indicates it is likely spheroidal.

History

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Discovery

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2002 AW197 was discovered on 10 January 2002, by astronomers at Palomar Observatory in San Diego County, California, United States.[1] Astronomers involved in the discovery were Michael Brown, Chad Trujillo, Eleanor Helin, Michael Hicks, Kenneth Lawrence and Steven Pravdo.[2] The object was discovered during Brown and Trujillo's Caltech Wide Area Sky Survey, which used Palomar Observatory's 1.22-meter (48 in) Samuel Oschin telescope to search for bright Kuiper belt objects.[17]: 100, 103  This survey, which was operated jointly with the nightly Near Earth Asteroid Tracking (NEAT) program at Palomar,[17]: 100  would later discover several other large objects beyond Neptune, including the dwarf planets Eris, Sedna, and Quaoar.[18]: 214 

2002 AW197 was found through manual vetting of potential moving objects identified by Brown and Trujillo's automatic image-searching software.[17]: 101  In terms of absolute magnitude, 2002 AW197 was the second-brightest Kuiper belt object known at the time.[19] It was detected at a red-filter apparent magnitude of 19.7.[2] 2002 AW197 was further observed by Trujillo and Brown using telescopes at Palomar and Mauna Kea Observatory during February to April 2002.[2] The discovery was announced by the Minor Planet Center on 20 July 2002 and the object was given the minor planet provisional designation of 2002 AW197.[2]

The 1.2-meter Samuel Oschin telescope that was used to discover 2002 AW197 at Palomar Observatory
Discovery images of 2002 AW197 from 10 January 2002

Further observations

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Within a month after 2002 AW197's discovery, Trujillo and Brown collaborated with Jean-Luc Margot and Frank Bertoldi to measure the object's diameter and thermal emission using the IRAM 30m radio telescope at Sierra Nevada, Spain.[20][19] Astronomers also found additional observations of 2002 AW197 from the time before and during its discovery, which allowed for further refinement of orbit calculations.[21] The earliest pre-discovery observation of 2002 AW197 comes from an image taken on 29 December 1997 by the NEAT/GEODSS program at Haleakalā Observatory, Hawaii.[1][21] As of 2025, 2002 AW197 has been observed for over 27 years, or about 8% of its orbital period.[3][1]

Numbering and naming

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2002 AW197 received its permanent minor planet catalog number of 55565 from the Minor Planet Center on 16 February 2003.[22]: 324  As of yet, it remains unnamed and the discoverers' privilege for naming this object expired ten years after its numbering.[1][23]: 6  Per naming guidelines by the International Astronomical Union's Working Group for Small Bodies Nomenclature, 2002 AW197 is open for name suggestions that pertain to creation myths, as required for Kuiper belt objects in general.[23]: 8 

Orbit and classification

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2002 AW197's orbit is outside that of Pluto's, with a higher inclination and different orientation
Diagram showing top and tilted views of the orbits of 2002 AW197 (pink), Pluto (purple) and the outer planets

2002 AW197 is a trans-Neptunian object (TNO) orbiting the Sun at a semi-major axis or average distance of 47.2 astronomical units (AU).[6][b] It follows an elliptical orbit with an eccentricity of 0.13.[6] During its 324-year orbital period, 2002 AW197 comes within 41.1 AU from the Sun at perihelion and up to 53.3 AU at aphelion.[6] It has an orbital inclination of 24.4° with respect to the ecliptic.[6] 2002 AW197 last passed perihelion in July 1753 and will make its next perihelion passage in May 2078.[25][7]

2002 AW197 is located in the classical region of the Kuiper belt 39–48 AU from the Sun,[4]: 53  and is thus classified as a classical Kuiper belt object or cubewano.[4]: 55  2002 AW197's high orbital inclination qualifies it as a dynamically "hot" member of the classical Kuiper belt, which implies that it was gravitationally scattered out to its present location by Neptune's outward planetary migration in the Solar System's early history.[26]: 230  Hence, 2002 AW197 is sometimes classified as a "scattered" object.[5][27]: 165 

Physical characteristics

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History of diameter estimates for 2002 AW197
Year of
Publication		 Diameter
(km)		 Method Refs
2002 886+115
−131 		thermal
(IRAM) 		[19][28]: 187 
2005 700±50 thermal
(Spitzer) 		[29][30]
2008 734.6+116.4
−108.3 		thermal
(Spitzer) 		[27]: 172 
2009 742+98
−104 		thermal
(Spitzer, remodeled) 		[31]: 291 
2014 768±39 thermal
(Herschel + Spitzer) 		[8]


Size, shape, and rotation

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Pair of far-infrared images of 2002 AW197 by the Spitzer Space Telescope

Measurements of 2002 AW197's infrared thermal emission by the Herschel and Spitzer space telescopes give a diameter of 768+39
−38 km (477+24
−24 mi).[8] This makes 2002 AW197 slightly smaller than the dwarf planet Ceres.[19] It is one of the largest unnamed Solar System objects with a measured diameter, tied with 2013 FY27 to within uncertainties (diameter 742+78
−83 km).[32] 2002 AW197 is large enough that some astronomers consider it a dwarf planet candidate.[33][34]: 178  2002 AW197's brightness fluctuates very little as it rotates, which could indicate it has a spheroidal shape.[35]: 856–857 [34]: 177 

2002 AW197 likely has a rotation period of around 8.8 hours, according to telescopic observations of its brightness changes over time. 2002 AW197's subtle brightness variations can make it difficult to determine its light curve and true rotation period.[11]: 6  The first measurements of 2002 AW197's rotation period made during 2002–2003 obtained a likely period of 8.86±0.01 hours.[9]: 6 [10]: 1132–1133  Although other alias periods of 13.94, 6.49, and 15.82 hours are possible, the 8.86 hour period stands out as the most likely.[10]: 1135  Observations from 2003–2004 obtained a period of 8.78 hours,[11]: 6  whereas another set of observations from 2003 could not determine a period.[36]: 790, 795 

Surface

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2002 AW197 has a dark, reddish surface with a geometric albedo of about 11%.[8] The visible and near-infrared spectrum of 2002 AW197 lacks obvious absorption features, which suggests that tholins mostly cover its surface.[37]

See also

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Notes

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  1. ^ The Minor Planet Center lists "Palomar" as the discoverer without listing specific people.[1]
  2. ^ These orbital elements are expressed in terms of the Solar System Barycenter (SSB) as the frame of reference.[6] Due to planetary perturbations, the Sun revolves around the SSB at non-negligible distances, so heliocentric-frame orbital elements and distances can vary in short timescales as shown in JPL-Horizons.[24]

References

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  1. ^ a b c d e f g h i "(55565) = 2002 AW197". Minor Planet Center. Retrieved 9 March 2025.
  2. ^ a b c d e Brown, M. E.; Trujillo, C. A.; Helin, E. F.; Pravdo, S.; Lawrence, K.; Hicks, M.; Marsden, B. G. (20 July 2002). "MPEC 2002-O30 : 2002 AW197". Minor Planet Electronic Circular. 2002-O30. Minor Planet Center. Bibcode:2002MPEC....O...30B. Retrieved 19 June 2025.
  3. ^ a b c d e "JPL Small-Body Database Lookup: 55565 (2002 AW197)" (2023-05-17 last obs.). Jet Propulsion Laboratory. Retrieved 19 June 2025.
  4. ^ a b c Gladman, Brett; Marsden, Brian G.; VanLaerhoven, Christa (2008). "Nomenclature in the Outer Solar System" (PDF). The Solar System Beyond Neptune. University of Arizona Press. pp. 43–57. arXiv:astro-ph/0702538. Bibcode:2008ssbn.book...43G. ISBN 9780816527557. S2CID 14469199. Archived from the original (PDF) on 1 August 2023.
  5. ^ a b Buie, Marc W. "Orbit Fit and Astrometric record for 55565". Southwest Research Institute. Archived from the original on 25 January 2025. Retrieved 19 June 2025.
  6. ^ a b c d e f "JPL Horizons On-Line Ephemeris for 55565 (2002 AW197) at epoch JD 2460000.5". JPL Horizons On-Line Ephemeris System. Jet Propulsion Laboratory. Retrieved 19 June 2025. Solution using the Solar System Barycenter. Ephemeris Type: Elements and Center: @0)
  7. ^ a b "JPL Horizons On-Line Ephemeris for 55565 (2002 AW197) from 2078-Apr-01 to 2078-Jun-01". JPL Horizons On-Line Ephemeris System. Jet Propulsion Laboratory. Retrieved 19 June 2025. (Perihelion occurs when deldot changes from negative to positive. Uncertainty in time of perihelion is 1-sigma from JPL Small-Body Database.)
  8. ^ a b c d e Vilenius, E.; Kiss, C.; Müller, T.; Mommert, M.; Santos-Sanz, P.; Pál, A.; et al. (April 2014). ""TNOs are Cool": A survey of the trans-Neptunian region. X. Analysis of classical Kuiper belt objects from Herschel and Spitzer observations". Astronomy and Astrophysics. 564: 18. arXiv:1403.6309v1. Bibcode:2014A&A...564A..35V. doi:10.1051/0004-6361/201322416. S2CID 118513049.
  9. ^ a b Lellouch, E.; Santos-Sanz, P.; Lacerda, P.; Mommert, M.; Duffard, R.; Ortiz, J. L.; et al. (September 2013). ""TNOs are Cool": A survey of the trans-Neptunian region. IX. Thermal properties of Kuiper belt objects and Centaurs from combined Herschel and Spitzer observations". Astronomy & Astrophysics. 557 (A60): 19. arXiv:1403.6309. Bibcode:2013A&A...557A..60L. doi:10.1051/0004-6361/201322416.
  10. ^ a b c 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.
  11. ^ a b c 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. S2CID 54039561.
  12. ^ a b "LCDB Data for (55565)". Asteroid Lightcurve Database (LCDB). Retrieved 9 March 2018.
  13. ^ a b 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.
  14. ^ a b Tegler, S. C.; Romanishin, W.; Consolmagno, G. J.; J., S. (December 2016). "Two Color Populations of Kuiper Belt and Centaur Objects and the Smaller Orbital Inclinations of Red Centaur Objects". The Astronomical Journal. 152 (6): 13. Bibcode:2016AJ....152..210T. doi:10.3847/0004-6256/152/6/210. S2CID 125183388.
  15. ^ "AstDys (55565) 2002AW197 Ephemerides". Department of Mathematics, University of Pisa, Italy. Retrieved 14 December 2013.
  16. ^ Vilenius, E.; Kiss, C.; Müller, T.; Mommert, M.; Santos-Sanz, P.; Pál, A.; et al. (April 2014). ""TNOs are Cool": A survey of the trans-Neptunian region X. Analysis of classical Kuiper belt objects from Herschel and Spitzer observations". Astronomy & Astrophysics. 564 (A35): 18. arXiv:1403.6309. Bibcode:2014A&A...564A..35V. doi:10.1051/0004-6361/201322047.
  17. ^ a b c Trujillo, C. A.; Brown, M. E. (June 2003). "The Caltech Wide Area Sky Survey". Earth, Moon, and Planets. 92 (1): 99–112. Bibcode:2003EM&P...92...99T. doi:10.1023/B:MOON.0000031929.19729.a1. S2CID 189905639.
  18. ^ Schilling, Govert (2008). The Hunt For Planet X. Springer. p. 214. ISBN 978-0-387-77804-4.
  19. ^ a b c d Margot, J.-L.; Trujillo, C.; Brown, M. E.; Bertoldi, F. (September 2002). The size and albedo of KBO 2002 AW197. American Astronomical Society, DPS Meeting #34. Vol. 34. Bibcode:2002DPS....34.1703M. 17.03.
  20. ^ Trujillo, C.; Brown, M. E.; Margot, J.-L.; Bertoldi, F. (September 2002). A Search for the Brightest Kuiper Belt Objects. American Astronomical Society, DPS Meeting #34. Vol. 34. p. 849. Bibcode:2002DPS....34.0904T. 09.04.
  21. ^ a b Sarneczky, K.; Kiss, L.; Helin, E. F.; Pravdo, S.; Lawrence, K. J.; Rabinowitz, D. L.; et al. (5 September 2002). "MPEC 2002-R12 : 2002 AW197". Minor Planet Electronic Circular. 2002-R12. Minor Planet Center. Bibcode:2002MPEC....R...12S. Retrieved 19 June 2025.
  22. ^ "M.P.C. 47762" (PDF). Minor Planet Circulars (47762). Minor Planet Center: 324. 16 February 2005. Retrieved 19 June 2025.
  23. ^ a b "Rules and Guidelines for Naming Non-Cometary Small Solar-System Bodies" (PDF). IAU Working Group for Small Bodies Nomenclature. 22 February 2025. Retrieved 19 June 2025.
  24. ^ "JPL Horizons On-Line Ephemeris for 55565 (2002 AW197) at epochs JD 2450000.5–2460000.5". JPL Horizons On-Line Ephemeris System. Jet Propulsion Laboratory. Retrieved 19 June 2025. Solution using the Sun. Ephemeris Type: Elements and Center: @sun)
  25. ^ "JPL Horizons On-Line Ephemeris for 55565 (2002 AW197) from 1753-Jun-20 to 1754-Jul-20". JPL Horizons On-Line Ephemeris System. Jet Propulsion Laboratory. Retrieved 19 June 2025. (Perihelion occurs when deldot changes from negative to positive. Uncertainty in time of perihelion is 1-sigma from JPL Small-Body Database.)
  26. ^ Lykawka, Patryk Sofia; Tadashi, Mukai (July 2007). "Dynamical classification of trans-neptunian objects: Probing their origin, evolution, and interrelation". Icarus. 189 (1): 213–232. Bibcode:2007Icar..189..213L. doi:10.1016/j.icarus.2007.01.001. S2CID 122671996.
  27. ^ a b Stansberry, John; Grundy, Will; Brown, Mike; Cruikshank, Dale; Spencer, John; Trilling, David; Margot, Jean-Luc (2008). "Physical Properties of Kuiper Belt and Centaur Objects: Constraints from the Spitzer Space Telescope" (PDF). The Solar System Beyond Neptune. University of Arizona Press. pp. 161–179. arXiv:astro-ph/0702538. Bibcode:2008ssbn.book..161S. ISBN 9780816527557. S2CID 578439.
  28. ^ Grundy, W. M.; Noll, K. S.; Stephens, D. C. (July 2005). "Diverse albedos of small trans-neptunian objects". Icarus. 176 (1): 184–191. arXiv:astro-ph/0502229. Bibcode:2005Icar..176..184G. doi:10.1016/j.icarus.2005.01.007. S2CID 118866288.
  29. ^ Cruikshank, Dale P.; Stansberry, John A.; Emery, Joshua P.; Fernández, Yanga R.; Werner, Michael W.; Trilling, David E.; et al. (May 2005). "The High-Albedo Kuiper Belt Object (55565) 2002 AW197". The Astrophysical Journal. 624 (1): L53 – L56. Bibcode:2005ApJ...624L..53C. doi:10.1086/430420.
  30. ^ Stansberry, J. A.; Cruikshank, D. P.; Grundy, W. G.; Margot, J. L.; Emery, J. P.; Fernandez, Y. R.; et al. (August 2005). "Albedos, Diameters (and a Density) of Kuiper Belt and Centaur Objects". American Astronomical Society. 37: 737. Bibcode:2005DPS....37.5205S.
  31. ^ Brucker, M. J.; Grundy, W. M.; Stansberry, J. A.; Spencer, J. R.; Sheppard, S. S.; Chiang, E. I.; Buie, M. W. (May 2009). "High albedos of low inclination Classical Kuiper belt objects". Icarus. 201 (1): 284–294. arXiv:0812.4290. Bibcode:2009Icar..201..284B. doi:10.1016/j.icarus.2008.12.040. S2CID 53543791.
  32. ^ Sheppard, Scott S.; Fernandez, Yanga F.; Moullet, Arielle (December 2018). "The Albedos, Sizes, Colors, and Satellites of Dwarf Planets Compared with Newly Measured Dwarf Planet 2013 FY27". The Astronomical Journal. 156 (6): 11. arXiv:1809.02184. Bibcode:2018AJ....156..270S. doi:10.3847/1538-3881/aae92a. S2CID 119522310. 270.
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  34. ^ a b Tancredi, Gonzalo (6 April 2010). "Physical and dynamical characteristics of icy "dwarf planets" (plutoids)". Proceedings of the International Astronomical Union. 5 (S263): 173–185. Bibcode:2010IAUS..263..173T. doi:10.1017/S1743921310001717.
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  36. ^ Sheppard, Scott S. (August 2007). "Light Curves of Dwarf Plutonian Planets and other Large Kuiper Belt Objects: Their Rotations, Phase Functions, and Absolute Magnitudes". The Astronomical Journal. 134 (2): 787–798. arXiv:0704.1636. Bibcode:2007AJ....134..787S. doi:10.1086/519072. S2CID 56247384.
  37. ^ D. Ragozzine; M. E. Brown (2007). "Candidate Members and Age Estimate of the Family of Kuiper Belt Object 2003 EL61". The Astronomical Journal. 134 (6): 2160–2167. arXiv:0709.0328. Bibcode:2007AJ....134.2160R. doi:10.1086/522334. S2CID 8387493.
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