4792 Lykaon (// lye-KAY-ən), provisional designation 1988 RK1, is a dark Jupiter trojan from the Trojan camp, approximately 51 kilometers (32 miles) in diameter. It was discovered on 10 September 1988, by American astronomer Carolyn Shoemaker at the Palomar Observatory in California. The possibly elongated Jovian asteroid belongs to the 100 largest Jupiter trojans and has a long rotation period of 40.1 hours. It was named after the Trojan prince Lycaon from Greek mythology.
|Discovered by||C. Shoemaker|
|Discovery site||Palomar Obs.|
|Discovery date||10 September 1988|
|MPC designation||(4792) Lykaon|
|Pronunciation||// · lye-KAY-ən|
|1988 RK1 · 1989 UN9|
|Jupiter trojan |
Trojan  · background 
|Orbital characteristics |
|Epoch 23 March 2018 (JD 2458200.5)|
|Uncertainty parameter 0|
|Observation arc||29.69 yr (10,843 d)|
|12.06 yr (4,406 d)|
|0° 4m 54.12s / day|
|Jupiter MOID||0.0079 AU|
53.16 km (calculated)
B–V = 0.830±0.060
V–R = 0.420±0.040
V–I = 0.960±0.025
Orbit and classificationEdit
Lykaon is a dark Jovian asteroid in a 1:1 orbital resonance with Jupiter. It is located in the trailering Trojan camp at the Gas Giant's L5 Lagrangian point, 60° behind its orbit . It is also a non-family asteroid of the Jovian background population. It orbits the Sun at a distance of 4.8–5.7 AU once every 12 years and 1 month (4,406 days; semi-major axis of 5.26 AU). Its orbit has an eccentricity of 0.09 and an inclination of 9° with respect to the ecliptic. The body's observation arc begins at Palomar with its official discovery observation in September 1988.
In April 1996, a rotational lightcurve of Lykaon was obtained from a total of six nights of photometric observations by Italian astronomer Stefano Mottola, using the Bochum 0.61-metre Telescope at La Silla Observatory in northern Chile. Lightcurve analysis gave a rotation period of 40.09±0.10 hours with a brightness variation of 0.43 magnitude (U=2+). A high brightness amplitude is indicative of a non-spherical shape. While not being a slow rotator, it has one of the longest periods among all larger Jupiter trojans (see table below).
Diameter and albedoEdit
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Lykaon measures 50.87 kilometers in diameter and its surface has an albedo of 0.068, while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for a carbonaceous asteroid of 0.057, and calculates a diameter of 53.16 kilometers based on an absolute magnitude of 10.1. No diameter estimate for this object was published by the IRAS and Akari (satellite) surveys.
This minor planet was named by the discoverer from Greek mythology after the Trojan prince Lycaon, one of King Priam's many sons. He was captured by Achilles and sold as slave. Shortly after Lycaon returned to the Trojan War, he was slain by Achilles without mercy near the River Scamander. The official naming citation was published by the Minor Planet Center on 27 June 1991 (M.P.C. 18465).
- "4792 Lykaon (1988 RK1)". Minor Planet Center. Retrieved 20 June 2018.
- "JPL Small-Body Database Browser: 4792 Lykaon (1988 RK1)" (2018-05-19 last obs.). Jet Propulsion Laboratory. Retrieved 20 June 2018.
- "List of Jupiter Trojans". Minor Planet Center. 1 June 2018. Retrieved 20 June 2018.
- "Asteroid (4792) Lykaon – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 20 June 2018.
- Grav, T.; Mainzer, A. K.; Bauer, J. M.; Masiero, J. R.; Nugent, C. R. (November 2012). "WISE/NEOWISE Observations of the Jovian Trojan Population: Taxonomy". The Astrophysical Journal. 759 (1): 10. arXiv:1209.1549. Bibcode:2012ApJ...759...49G. doi:10.1088/0004-637X/759/1/49. (online catalog)
- "LCDB Data for (4792) Lykaon". Asteroid Lightcurve Database (LCDB). Retrieved 20 June 2018.
- Mottola, Stefano; Di Martino, Mario; Erikson, Anders; Gonano-Beurer, Maria; Carbognani, Albino; Carsenty, Uri; et al. (May 2011). "Rotational Properties of Jupiter Trojans. I. Light Curves of 80 Objects". The Astronomical Journal. 141 (5): 32. Bibcode:2011AJ....141..170M. doi:10.1088/0004-6256/141/5/170.
- Carvano, J. M.; Hasselmann, P. H.; Lazzaro, D.; Mothé-Diniz, T. (February 2010). "SDSS-based taxonomic classification and orbital distribution of main belt asteroids". Astronomy and Astrophysics. 510: 12. Bibcode:2010A&A...510A..43C. doi:10.1051/0004-6361/200913322. Retrieved 20 June 2018.
- Chatelain, Joseph P.; Henry, Todd J.; French, Linda M.; Winters, Jennifer G.; Trilling, David E. (June 2016). "Photometric colors of the brightest members of the Jupiter L5 Trojan cloud". Icarus. 271: 158–169. Bibcode:2016Icar..271..158C. doi:10.1016/j.icarus.2016.01.026.
- "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 20 June 2018.
- Asteroid Lightcurve Database (LCDB), query form (info)
- Dictionary of Minor Planet Names, Google books
- Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
- Asteroid 4792 Lykaon at the Small Bodies Data Ferret
- 4792 Lykaon at AstDyS-2, Asteroids—Dynamic Site
- 4792 Lykaon at the JPL Small-Body Database