|Discovered by||C. S. Shoemaker|
E. M. Shoemaker
|Discovery site||Palomar Obs.|
|Discovery date||20 February 1990|
|MPC designation||(5436) Eumelos|
|1990 DK · 1986 XF2|
|Jupiter trojan |
Greek  · background 
|Orbital characteristics |
|Epoch 23 March 2018 (JD 2458200.5)|
|Uncertainty parameter 0|
|Observation arc||30.51 yr (11,142 d)|
|11.86 yr (4,333 d)|
|0° 4m 59.16s / day|
|Jupiter MOID||0.1684 AU|
|±0.02 h 38.41(ambiguous)[a]|
5436 Eumelos, provisional designation 1990 DK, is a mid-sized Jupiter trojan from the Greek camp, approximately 38 kilometers (24 miles) in diameter. It was discovered on 20 February 1990, by American astronomers Carolyn and Eugene Shoemaker at the Palomar Observatory in California. The dark Jovian asteroid has been identified as the principal body of the small Eumelos family and is likely elongated in shape with a longer-than-average rotation period of 38.4 hours. It was named after the Greek warrior and charioteer Eumelus from Greek mythology.
Orbit and classification
Eumelos is a dark Jovian asteroid in a 1:1 orbital resonance with Jupiter. It is located in the leading Greek camp at the Gas Giant's L4 Lagrangian point, 60° ahead on its orbit . It orbits the Sun at a distance of 4.8–5.6 AU once every 11 years and 10 months (4,333 days; semi-major axis of 5.2 AU). Its orbit has an eccentricity of 0.08 and an inclination of 7° with respect to the ecliptic.
Fernando Roig and Ricardo Gil-Hutton identified Eumelos as the principal body of a small Jovian asteroid family, using the hierarchical clustering method (HCM), which looks for groupings of neighboring asteroids based on the smallest distances between them in the proper orbital element space. According to the astronomers, the Eumelos family belongs to the larger Menelaus clan, an aggregation of Jupiter trojans which is composed of several families, similar to the Flora family in the inner asteroid belt.:9,10
However this family is not included in David Nesvorný's HCM-analysis from 2014. Instead, Eumelos is listed as a non-family asteroid of the Jovian background population on the Asteroids Dynamic Site (AstDyS) which based on another analysis by Milani and Knežević.
This minor planet was named after Eumelus (Eumelos), son of King Admetus and leader of the Greek contingent from Pherae in the Trojan War. At funeral games for Patroclus, he was the fifth and last in the chariot races competing against Diomedes, Menelaus, Antilochus and Meriones. Though Eumelus came in last, he was awarded by Achilles with the bronze corselet stripped from the Trojan Asteropaios (see table below for the correspondingly named Jupiter trojans). The official naming citation was published by the Minor Planet Center on 12 July 1995 (M.P.C. 25444).
In 2013, a rotational lightcurve of Eumelos was obtained from photometric observations by Linda French and Lawrence Wasserman at the Anderson Mesa Station of the Lowell Observatory, using its 0.8-meter NURO telescope over three consecutive nights until 1 March 2013. Robert Stephens at the Center for Solar System Studies in Landers, California, then observed this asteroid for five more nights during 10–14 March 2013. Lightcurve analysis gave a well-defined rotation period of ±0.02 hours with a brightness amplitude of 0.68 38.41magnitude, indicative of a non-spherical shape (U=3).[a]
In August 2015, observations by the Kepler space telescope during its K2 mission gave two lightcurves with an alternative period of ±0.37 and 21.23±0.315 hours with a brightness variation of 0.40 and 0.43 magnitude, respectively ( 21.276U=2/2). The Collaborative Asteroid Lightcurve Link (CALL), labels the period determination for this asteroid as ambiguous.
Diameter and albedo
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Eumelos measures 37.70 kilometers in diameter and its surface has an albedo of 0.086, while CALL assumes a standard albedo for a carbonaceous asteroid of 0.057 and calculates a diameter of 46.30 kilometers based on an absolute magnitude of 10.4.
- "5436 Eumelos (1990 DK)". Minor Planet Center. Retrieved 29 June 2018.
- "JPL Small-Body Database Browser: 5436 Eumelos (1990 DK)" (2017-06-03 last obs.). Jet Propulsion Laboratory. Retrieved 29 June 2018.
- "List of Jupiter Trojans". Minor Planet Center. 1 June 2018. Retrieved 29 June 2018.
- "Asteroid (5436) Eumelos – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 29 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. Retrieved 29 June 2018. (online catalog)
- "LCDB Data for (5436) Eumelos". Asteroid Lightcurve Database (LCDB). Retrieved 29 June 2018.
- French, Linda M.; Stephens, Robert, D.; Coley, Daniel R.; Wasserman, Lawrence H.; Vilas, Faith; La Rocca, Daniel (October 2013). "A Troop of Trojans: Photometry of 24 Jovian Trojan Asteroids". The Minor Planet Bulletin. 40 (4): 198–203. Bibcode:2013MPBu...40..198F. ISSN 1052-8091. Retrieved 29 June 2018.
- Roig, F.; Ribeiro, A. O.; Gil-Hutton, R. (June 2008). "Taxonomy of asteroid families among the Jupiter Trojans: comparison between spectroscopic data and the Sloan Digital Sky Survey colors" (PDF). Astronomy and Astrophysics. 483 (3): 911–931. arXiv:0712.0046. Bibcode:2008A&A...483..911R. doi:10.1051/0004-6361:20079177. Retrieved 29 June 2018.
- Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). "Identification and Dynamical Properties of Asteroid Families" (PDF). Asteroids IV: 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. Retrieved 29 June 2017.
- "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 29 June 2018.
- Ryan, Erin Lee; Sharkey, Benjamin N. L.; Woodward, Charles E. (March 2017). "Trojan Asteroids in the Kepler Campaign 6 Field". The Astronomical Journal. 153 (3): 12. Bibcode:2017AJ....153..116R. doi:10.3847/1538-3881/153/3/116. Retrieved 29 June 2018.
- Szabó, Gy. M.; Pál, A.; Kiss, Cs.; Kiss, L. L.; Molnár, L.; Hanyecz, O.; et al. (March 2017). "The heart of the swarm: K2 photometry and rotational characteristics of 56 Jovian Trojan asteroids" (PDF). Astronomy and Astrophysics. 599: 13. arXiv:1609.02760. Bibcode:2017A&A...599A..44S. doi:10.1051/0004-6361/201629401. Retrieved 29 June 2018.
- Asteroid Lightcurve Database (LCDB), query form (info)
- Dictionary of Minor Planet Names, Google books
- Discovery Circumstances: Numbered Minor Planets (5001)-(10000) – Minor Planet Center
- Asteroid 5436 Eumelos at the Small Bodies Data Ferret
- 5436 Eumelos at AstDyS-2, Asteroids—Dynamic Site
- 5436 Eumelos at the JPL Small-Body Database