38628 Huya

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38628 Huya
Discovered by I. R. Ferrin
Discovery date 10 March 2000
MPC designation 38628 Huya
Pronunciation /hˈjɑː/ hoo-YAH
Named after
2000 EB173
Orbital characteristics[1][3]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 2
Observation arc 7010 days (19.19 yr)
Aphelion 50.723 AU (7.5881 Tm)
Perihelion 28.533 AU (4.2685 Tm)
39.628 AU (5.9283 Tm)
Eccentricity 0.27997
249.47 yr (91117.9 d)
4.63 km/s
0° 0m 14.223s / day
Inclination 15.463°
Known satellites 1
Earth MOID 27.5533 AU (4.12192 Tm)
Jupiter MOID 23.3093 AU (3.48702 Tm)
Jupiter Tisserand parameter 5.238
Physical characteristics
Dimensions 406±16 km[4]
5.28 h (0.220 d)
13.5 hr(?)[3]
0.083 ± 0.004[4]
Temperature ≈44 K
B−V=0.95 ± 0.05
V−R=0.57 ± 0.09[5]
19.3 (opposition)[6]
5.04 ± 0.03[4]
5.37 ± 0.04[7]
0.020″ (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 shows only small deviations, suggesting that Huya 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]



Huya was discovered in March 2000 by Ignacio Ferrin and announced on 24 October 2000. At the time of its discovery, Huya was the brightest (and hence estimated to be the biggest) trans-Neptunian object found since Pluto. It was found using data collected at the CIDA Observatory in Venezuela.


It was named Huya, after Juyá the Wayuu rain god, in August 2003 by the International Astronomical Union (IAU).

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 of 458.7±9.2 km.[4] Taking into account that Huya is a binary the diameter of the primary is estimated at 406±16 km.[4]

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]

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

Huya is currently 28.5 AU from the Sun[6] and it came 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.

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]


A satellite, reported in IAU Circular 9253 on 12 July 2012, was discovered by Keith S. Noll, William M. Grundy, Hilke E. Schlichting, Ruth Murray-Clay and Susan 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 213±30 km[4] and a separation of 1,800 kilometres (1,100 mi) from primary. Its provisional designation is S/2012 38628 Huya 1.


  1. ^ Angular size at May 2015 opposition: arctan (406 km in diameter / (27.5543 AU * 149597870.7 km)) = 0.020″


  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 f "38628 Huya (2000 EB173)". JPL Small-Body Database. Jet Propulsion Laboratory. SPK-ID: 2038628. Retrieved 12 April 2016. 
  4. ^ a b c d e f g Fornasier, S.; Lellouch, E.; Müller, P., T.; et al. (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.". Astronomy & Astrophysics. 555: A92. arXiv:1305.0449v2free to read. Bibcode:2013A&A...555A..15F. doi:10.1051/0004-6361/201321329. 
  5. ^ 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:1202.3657free to read. 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. Archived from the original on 2011-10-18. 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/0702538free to read. 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/0105434free to read. 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. 

External links[edit]