38628 Huya

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38628 Huya
38628 Huya.png
Artist's impression of 38628 Huya
Discovery and designation
Discovered by Ignacio Ferrin
Discovery date March 10, 2000
MPC designation 38628 Huya
Pronunciation /hˈjɑː/ hoo-YAH
Named after
2000 EB173
Orbital characteristics[1][3]
Epoch January 4, 2010 (JD 2455200.5)
Aphelion 50.363 AU (7534 Gm)
Perihelion 28.520 AU (4266 Gm)
39.442 AU (5900 Gm)
Eccentricity 0.2768
247.72 yr (90477 d)
4.63 km/s
Inclination 15.487°
Known satellites 1
Physical characteristics
Dimensions 458.0±9.2 km[4]
13.5 hr(?)[3]
0.081 ± 0.011[5]
Temperature ≈44 K
B−V=0.95 ± 0.05
V−R=0.57 ± 0.09[5]
19.3 (opposition)[6]
5.14 ± 0.07[5]
5.37 ± 0.04 [7]
0.024″ (max)[note 1]

38628 Huya is a trans-Neptunian object (TNO). It is a plutino, being in a 2:3 mean-motion resonance with Neptune.[1] It has a diameter of 458.0±9.2 km,[4] and it is possibly a dwarf planet[8] (icy trans-Neptunian objects with a diameter above around 400 kilometres (250 mi) are expected to be spherical), although the IAU has never classified it as such.[9] Light-curve-amplitude analysis, which shows only small deviations, suggests that it is likely a spheroid with small albedo spots.[10] As of 2010, astronomer Gonzalo Tancredi thought that Huya was very probably a dwarf planet.[11]

It was discovered in March 2000 by Ignacio Ferrin and announced on 24 October 2000. It was assigned the name Huya, after Juyá the Wayuu rain god, in August 2003 by the International Astronomical Union (IAU).


A satellite, reported in IAU Circular 9253 on 12 July 2012, was discovered by K. S. Noll, W. M. Grundy, H. Schlichting, R. Murray-Clay and S. D. Benecchi from Hubble Space Telescope observations obtained on 6 May 2012 and confirmed in reexamination of Hubble Space Telescope imagery from 30 June-1 July 2012. It has an estimated diameter of 210±30 km and a separation of 1,800 kilometres (1,100 mi) from primary.


At the time of its discovery, Huya was the biggest and brightest trans-Neptunian object found since Pluto. It was found using data collected at the CIDA Observatory in Venezuela.

Physical characteristics[edit]

The Spitzer Space Telescope has estimated Huya to be about 530 kilometres (330 mi) in diameter with a low albedo of around 0.05.[12] The later termination, based on a combination of Spitzer and Herschel measurements, yielded a smaller size estimate of 438.7+26.5

Huya has a moderately red-sloped reflectance spectrum in the visible and near-infrared, suggesting a surface rich in organic material such as tholins.[13] There is a broad absorption feature near 2 μm possibly belonging to water ice or some water-altered material. Additional absorption features may be present near 0.6–0.8 μm, which may be caused by aqueously-altered anhydrous silicates.[14]

Orbit and rotation[edit]

Huya is currently 28.5 AU from the Sun[6] and will come to perihelion in December 2014.[3] This means that it is currently inside the orbit of the planet Neptune. Like Pluto, this plutino spends part of its orbit closer to the Sun than Neptune, even though their orbits are controlled by Neptune. Huya will be closer to the Sun than Neptune until about July 2029.[15] Simulations by the Deep Ecliptic Survey (DES) show that, over the next 10 million years, Huya can acquire a perihelion distance (qmin) as small as 27.28 AU.[1] Plutinos (15875) 1996 TP66 and (120216) 2004 EW95 get even closer to the Sun.

Plot of the distance to the Sun for Neptune, Pluto and Huya over a thousand-year period

Given the long orbit that TNOs have around the Sun, Huya comes to opposition in early May of each year at an apparent magnitude of 19.3.[6]

Huya has been observed 131 times, with precovery images back to 1996.[3] The rotation period of Huya is unknown:[16] although a value of 13.50 hours has been tentatively obtained from fragmentary light curve data, it may well be completely erroneous.[3]


  1. ^ Huya Angular Size at May 2015 Opposition: 480km dia / (27.5543AU * 149 597 870km) * 206265 = 0.024″


  1. ^ a b c d Buie, M. W. (22 April 2007). "Orbit Fit and Astrometric record for 38628". SwRI (Space Science Department). Retrieved 2008-07-17. 
  2. ^ "MPEC 2009-C70 :Distant Minor Planets (2009 FEB. 28.0 TT)". Minor Planet Center. 2009-02-10. Retrieved 2009-03-24. 
  3. ^ a b c d e "38628 Huya (2000 EB173)". JPL Small-Body Database. Jet Propulsion Laboratory. SPK-ID: 2038628. Retrieved 2008-07-17. 
  4. ^ a b S. Fornasier, E. Lellouch, T. Müller, P. Santos-Sanz, P. Panuzzo, C. Kiss, T. Lim, M. Mommert, D. Bockelée-Morvan, E. Vilenius, J. Stansberry, G.P. Tozzi, S. Mottola, A. Delsanti, J. Crovisier, R. Duffard, F. Henry, P. Lacerda, A. Barucci, & A. Gicquel (2013). TNOs are Cool: A survey of the trans-Neptunian region. VIII. Combined Herschel PACS and SPIRE observations of 9 bright targets at 70–500 µm.
  5. ^ a b c d e Mommert, M. et al. (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. 
  6. ^ a b c "AstDys (38628) Huya Ephemerides". Department of Mathematics, University of Pisa, Italy. Retrieved 2009-03-22. 
  7. ^ Doressoundiram, A. et al. (2007). "The Meudon Multicolor Survey (2MS) of Centaurs and Trans-Neptunian Objects: From Visible to Infrared Colors". The Astronomical Journal 134 (6): 2186. Bibcode:2007AJ....134.2186D. doi:10.1086/522783. 
  8. ^ Brown, M. E. (23 September 2011). "How many dwarf planets are there in the outer solar system? (updates daily)". California Institute of Technology. Retrieved 2011-09-23. 
  9. ^ Brown, M. E. "The Dwarf Planets". California Institute of Technology. Archived from the original on 29 January 2008. Retrieved 2008-01-20. 
  10. ^ Tancredi, G.; Favre, S. (2008). "Which are the dwarfs in the Solar System?". Icarus 195 (2): 851. Bibcode:2008Icar..195..851T. doi:10.1016/j.icarus.2007.12.020. 
  11. ^ Tancredi, G. (2009). "Physical and dynamical characteristics of icy "dwarf planets" (plutoids)". Proceedings of the International Astronomical Union 5: 173–15. Bibcode:2010IAUS..263..173T. doi:10.1017/S1743921310001717. 
  12. ^ Stansberry, J. et al. (2007). "Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope". In Barucci, M. A. et al. The Solar System Beyond Neptune. University of Arizona Press. pp. 161–179. arXiv:astro-ph/0702538. Bibcode:2008ssbn.book..161S. ISBN 978-0-8165-2755-7. 
  13. ^ Licandro, J.; Oliva, E.; Di Martino, M. (2001). "NICS-TNG infrared spectroscopy of trans-neptunian objects 2000 EB173 and 2000 WR106". Astronomy and Astrophysics 373 (3): L29–L32. arXiv:astro-ph/0105434. Bibcode:2001A&A...373L..29L. doi:10.1051/0004-6361:20010758. 
  14. ^ de Bergh, C. et al. (2004). "Aqueous altered silicates at the surface of two Plutinos?". Astronomy and Astrophysics 416 (2): 791–798. Bibcode:2004A&A...416..791D. doi:10.1051/0004-6361:20031727. 
  15. ^ "38628 Huya (2000 EB173) ephemeris". JPL Small-Body Database. Jet Propulsion Laboratory. SPK-ID: 2038628. Retrieved 2009-03-23. 
  16. ^ Sheppard, S. S.; Lacedra, P.; Ortiz, J. L. (2008). "Photometric Lightcurves of Transneptunian Objects and Centaurs: Rotations, Shapes, and Densities". In Barucci, A. M. et al. The Solar System Beyond Neptune (PDF). University of Arizona Press. pp. 129–142. ISBN 978-0-8165-2755-7. 

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