Misplaced Pages

18493 Demoleon (/dɪˈmoʊliən/provisional designation 1996 HV₉) is a Jupiter trojan from the Trojan camp, approximately 33 kilometers (21 miles) in diameter. It was discovered by Belgian astronomer Eric Elst at ESO's La Silla Observatory in northern Chile on 17 April 1996. The dark Jovian asteroid has a rotation period of 14.4 hours. It was named after the Trojan warrior Demoleon from Greek mythology.

Orbit and classification

Demoleon 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 on its orbit (see Trojans in astronomy). It is also a non-family asteroid of the Jovian background population. It orbits the Sun at a distance of 4.8–5.8 AU once every 12 years and 2 months (4,454 days; semi-major axis of 5.3 AU). Its orbit has an eccentricity of 0.09 and an inclination of 17° with respect to the ecliptic. The body's observation arc begins with a precovery published by the Digitized Sky Survey and taken at Palomar Observatory in November 1989, more than 6 years prior to its official discovery observation at La Silla.

Naming

This minor planet was named from Greek mythology after the Trojan warrior Demoleon, son of Antenor, who was a counselor to King Priam. Demoleon, a valiant champion of war was killed by Achilles, whose spear struck Demoleon on the temple through his bronze-cheeked helmet, crushing the bone so that the brain inside was shed in all directions. The official naming citation was published by the Minor Planet Center on 27 May 2010 (M.P.C. 70409).

Physical characteristics

Demoleon is an assumed C-type asteroid, while most larger Jupiter trojans are D-types. It has a low V–I color index of 0.775 (see table below).

Rotation period

In November 2014, a rotational lightcurve of Demoleon was obtained over a total of seven nights of photometric observations by Robert Stephens at the Center for Solar System Studies in Landers, California. Lightcurve analysis gave a rotation period of 14.43±0.01 hours with a brightness amplitude of 0.18 magnitude (U=2).

Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Demoleon measures 33.47 kilometers in diameter and its surface has an albedo of 0.083, while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for a carbonaceous asteroid of 0.057 and calculates a diameter of 40.33 kilometers based on an absolute magnitude of 10.7.

Notes

1. ^ Lightcurve plots of (18493) Demoleon from Nov 2014 by Robert Stephens at the Center for Solar System Studies (U81). Quality code is 2+ (lightcurve rating at CS3). Summary figures at the LCDB and CS3.

References

1. ^ "18493 Demoleon (1996 HV9)". Minor Planet Center. Retrieved 4 July 2018.
2. Noah Webster (1884) A Practical Dictionary of the English Language
3. ^ "JPL Small-Body Database Browser: 18493 Demoleon (1996 HV9)" (2018-02-24 last obs.). Jet Propulsion Laboratory. Retrieved 4 July 2018.
4. "List of Jupiter Trojans". Minor Planet Center. 1 July 2018. Retrieved 4 July 2018.
5. ^ "Asteroid (18493) Demoleon – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 4 July 2018.
6. ^ 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. S2CID 119101711. (online catalog)
7. ^ "LCDB Data for (18493) Demoleon". Asteroid Lightcurve Database (LCDB). Retrieved 4 July 2018.
8. ^ Stephens, Robert D.; Coley, Daniel R.; French, Linda M. (July 2015). "Dispatches from the Trojan Camp - Jovian Trojan L5 Asteroids Observed from CS3: 2014 October - 2015 January". The Minor Planet Bulletin. 42 (3): 216–224. Bibcode:2015MPBu...42R.216S. ISSN 1052-8091.
9. ^ Hainaut, O. R.; Boehnhardt, H.; Protopapa, S. (October 2012). "Colours of minor bodies in the outer solar system. II. A statistical analysis revisited". Astronomy and Astrophysics. 546: 20. arXiv:1209.1896. Bibcode:2012A&A...546A.115H. doi:10.1051/0004-6361/201219566. S2CID 54776793.
10. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 4 July 2018.

External links

• Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
• Dictionary of Minor Planet Names, Google books
• Discovery Circumstances: Numbered Minor Planets (15001)-(20000) – Minor Planet Center
• Asteroid 18493 Demoleon Archived 4 July 2018 at the Wayback Machine at the Small Bodies Data Ferret
• 18493 Demoleon at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 18493 Demoleon at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters

• Minor planet object articles (numbered)
• Jupiter trojans (Trojan camp)
• Discoveries by Eric Walter Elst
• Named minor planets
• Astronomical objects discovered in 1996