Astronomy:9694 Lycomedes

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9694 Lycomedes
009694-asteroid shape model (9694) Lycomedes.png
Shape model of Lycomedes from its lightcurve
Discovery [1]
Discovered byC. J. van Houten
I. van Houten-G.
T. Gehrels
Discovery sitePalomar Obs.
Discovery date26 September 1960
Designations
(9694) Lycomedes
Pronunciation/lɪkəˈmiːdiːz/[5]
Named afterLycomedes [1]
(Greek mythology)
6581 P-L · 1990 DY1
Minor planet categoryJupiter trojan [1][2]
Greek [3] · background [4]
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc57.65 yr (21,058 d)
|{{{apsis}}}|helion}}5.2852 AU
|{{{apsis}}}|helion}}4.9135 AU
5.0993 AU
Eccentricity0.0364
Orbital period11.52 yr (4,206 d)
Mean anomaly226.07°
Mean motion0° 5m 8.16s / day
Inclination4.9436°
Longitude of ascending node350.07°
53.908°
Jupiter MOID0.019 AU
TJupiter2.9920
Physical characteristics
Mean diameter31.74±0.24 km[6]
40.33 km (calculated)[7]
Rotation period18.2±0.1 h[8]
Geometric albedo0.057 (assumed)[7]
0.101±0.010[6]
C (assumed)[7]
Absolute magnitude (H)10.60[6]
10.7[1][2][7]


9694 Lycomedes /lɪkəˈmiːdiːz/ is a Jupiter trojan from the Greek camp, approximately 32 kilometers (20 miles) in diameter.[1] It was discovered during the Palomar–Leiden survey at the Palomar Observatory in 1960 and later named after Lycomedes from Greek mythology.[1] The dark Jovian asteroid is likely elongated in shape and has a rotation period of 18.2 hours.[7]

Discovery

Lycomedes was discovered on 26 September 1960, by Dutch astronomer couple Ingrid and Cornelis van Houten at Leiden, on photographic plates taken by astronomer Tom Gehrels at the Palomar Observatory in California.[1] The body's observation arc begins the night after its official discovery observation at Palomar.[1]

Palomar–Leiden survey

Naming

This minor planet was named from Greek mythology after Lycomedes, the Greek king of Scyros. At the request of Thetis, he concealed her son Achilles dressed in girl's clothes among his own daughters to save him from the Trojan War until Odysseus drew him out of his disguise.[1] The official naming citation was published by the Minor Planet Center on 2 April 1999 (M.P.C. 34355).[9]

Orbit and classification

As all Jupiter trojans, Lycomedes is 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 (see Trojans in astronomy).[3]

It orbits the Sun at a distance of 4.9–5.3 AU once every 11 years and 6 months (4,206 days; semi-major axis of 5.1 AU). Its orbit has an eccentricity of 0.04 and an inclination of 5° with respect to the ecliptic.[2]

Physical characteristics

Lycomedes is an assumed C-type asteroid, while most larger Jupiter trojans are D-types.[7]

Rotation period

In October 2010, a first rotational lightcurve of Lycomedes was obtained from photometric observations by astronomers at the Palomar Transient Factory in California. Lightcurve analysis gave a rotation period of 18.090±0.0211 hours with a brightness amplitude of 0.38 magnitude ({{{1}}}).[7][10]

In November 2011, follow-up observations over two consecutive nights were made by Daniel Coley at the Goat Mountain Astronomical Research Station (G79) in California. It gave a concurring rotation period of 18.2±0.1 hours with a high brightness amplitude of 0.55 magnitude, indicative of a non-spherical shape ({{{1}}}).[8][lower-alpha 1]

Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Lycomedes measures between 31.736 and 31.74 kilometers in diameter and its surface has an albedo,[6] 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.[7]

100+ largest Jupiter trojans

Notes

  1. ↑ Lightcurve plots of (9694) Lycomedes from Nov 2011 by Daniel Coley at GMARS (G79) and the Center for Solar System Studies (U80). Quality code is 3- (lightcurve rating at CS3). Summary figures at the LCDB and CS3.

References

  1. ↑ Jump up to: 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 "9694 Lycomedes (6581 P-L)". Minor Planet Center. https://www.minorplanetcenter.net/db_search/show_object?object_id=9694. 
  2. ↑ Jump up to: 2.0 2.1 2.2 2.3 "JPL Small-Body Database Browser: 9694 Lycomedes (6581 P-L)". Jet Propulsion Laboratory. https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009694. 
  3. ↑ Jump up to: 3.0 3.1 "List of Jupiter Trojans". Minor Planet Center. 1 July 2018. https://www.minorplanetcenter.net/iau/lists/JupiterTrojans.html. 
  4. ↑ "Asteroid (9694) Lycomedes – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. https://newton.spacedys.com/astdys/index.php?n=9694&pc=1.1.6. 
  5. ↑ Noah Webster (1884) A Practical Dictionary of the English Language
  6. ↑ Jump up to: 6.0 6.1 6.2 6.3 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. doi:10.1088/0004-637X/759/1/49. Bibcode: 2012ApJ...759...49G.  (online catalog)
  7. ↑ Jump up to: 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 "LCDB Data for (9694) Lycomedes". Asteroid Lightcurve Database (LCDB). http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=9694. 
  8. ↑ Jump up to: 8.0 8.1 French, Linda M.; Stephens, Robert D.; Coley, Daniel R.; Megna, Ralph; Wasserman, Lawrence H. (July 2012). "Photometry of 17 Jovian Trojan Asteroids". Minor Planet Bulletin 39 (3): 183–187. ISSN 1052-8091. Bibcode: 2012MPBu...39..183F. http://www.minorplanet.info/MPB/issues/MPB_39-3.pdf. Retrieved 23 March 2020. 
  9. ↑ "MPC/MPO/MPS Archive". Minor Planet Center. https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html. 
  10. ↑ Waszczak, Adam; Chang, Chan-Kao; Ofek, Eran O.; Laher, Russ; Masci, Frank; Levitan, David et al. (September 2015). "Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry". The Astronomical Journal 150 (3): 35. doi:10.1088/0004-6256/150/3/75. Bibcode: 2015AJ....150...75W. 
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