Astronomy:2920 Automedon

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Short description: Jupiter trojan asteroid
2920 Automedon
Discovery [1]
Discovered byE. Bowell
Discovery siteAnderson Mesa Stn.
Discovery date3 May 1981
Designations
(2920) Automedon
Pronunciation/ɔːˈtɒmɪdɒn/[6]
Named afterAutomedon [1]
(Greek mythology)
1981 JR
Minor planet categoryJupiter trojan [1][2][3]
Greek [4][5] · background [5]
AdjectivesAutomedontian
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc36.97 yr (13,502 d)
|{{{apsis}}}|helion}}5.2417 AU
|{{{apsis}}}|helion}}4.9742 AU
5.1079 AU
Eccentricity0.0262
Orbital period11.54 yr (4,217 d)
Mean anomaly221.03°
Mean motion0° 5m 7.44s / day
Inclination21.121°
Longitude of ascending node230.94°
197.70°
Jupiter MOID0.0311 AU
TJupiter2.8670
Physical characteristics
Mean diameter88.57±1.80 km[7]
111.01±7.5 km[8]
113.11±2.25 km[9]
Rotation period10.212±0.002 h[10]
10.220±0.004 h[11]
10.223±0.003 h[12][lower-alpha 1]
Geometric albedo0.042±0.002[9]
0.0433±0.007[8]
0.068±0.009[7]
D (SMASS-1)[13]
C (assumed)[3]
V–I = 0.950±0.015[3]
Absolute magnitude (H)8.59±0.21[14]
8.80[2][7][8][9]


2920 Automedon /ɔːˈtɒmɪdɒn/ is a large Jupiter trojan from the Greek camp, approximately 110 kilometers (68 miles) in diameter. It was discovered by American astronomer Edward Bowell at the Anderson Mesa station of the Lowell Observatory on 3 May 1981.[1] The dark D-type asteroid has a rotation period of 10.22 hours and belongs to the 30 largest Jupiter trojans.[3] It was named after the ancient Greek hero Automedon, the charioteer of Achilles.[1]

Orbit and classification

Automedon is a dark Jovian asteroid orbiting in the leading Greek camp at Jupiter's L4 Lagrangian point, 60° ahead of its orbit in a 1:1 resonance (see Trojans in astronomy). It is a non-family asteroid in the Jovian background population.[5][13]

It orbits the Sun at a distance of 5.0–5.2 AU once every 11 years and 6 months (4,217 days; semi-major axis of 5.11 AU). Its orbit has an eccentricity of 0.03 and an inclination of 21° with respect to the ecliptic.[2] The body's observation arc begins with its official discovery observation at Anderson Mesa.[1]

Physical characteristics

In the SMASS classification, Automedon is a dark D-type asteroid (first SMASS survey, Xu 1995).[13] It is also a generically assumed C-type asteroid.[3]

Rotation period

Three rotational lightcurves of Automedon have been obtained from photometric observations, that are all in good agreement.[3]

In June 1994, observations by Stefano Mottola using the now decommissioned Bochum 0.61-metre Telescope at ESO's La Silla Observatory in Chile gave a rotation period of 10.220 hours with a brightness variation of 0.12 magnitude ({{{1}}}).[11]

A second lightcurve gave a period of 10.212 hours with an amplitude of 0.17 magnitude. It was measured in July 2007, by astronomers using telescopes at the Calvin College Observatory (H62) in Michigan and the Calvin-Rehoboth Robotic Observatory in New Mexico ({{{1}}}).[10] In June 2017, another observation by Brian Warner and Robert Stephens at the Center for Solar System Studies (U81) in California gave a period of 10.223 hours with an amplitude of 0.11 magnitude ({{{1}}}).[12][lower-alpha 1]

Diameter and albedo

According to the surveys carried out by the Japanese Akari satellite, the Infrared Astronomical Satellite IRAS, and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Automedon measures between 88.57 and 113.11 kilometers in diameter and its surface has an albedo between 0.042 and 0.068.[7][8][9]

The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0433 and a diameter of 111.01 kilometers based on an absolute magnitude of 8.8.[3]

100+ largest Jupiter trojans

Naming

This minor planet was named after the Greek mythology hero Automedon, Greek mythology. He was the son of Diorês and the charioteer of Greek hero Achilles during the Trojan War. Automedon took revenge for the death of Patroclus by killing the Trojan Aretus.[1] The official naming citation was published by the Minor Planet Center on 17 February 1984 (M.P.C. 8544).[15]

Notes

  1. ↑ Jump up to: 1.0 1.1 Lightcurve plot of (2920) Automedon from June 2017 by Brian Warner and Robert Stephens at the Center for Solar System Studies (U81). Rotation period 10.223±0.003 hours with an amplitude of 0.11 mag. Quality code is 3-. Summary figures at the LCDB.

References

  1. ↑ Jump up to: 1.0 1.1 1.2 1.3 1.4 1.5 1.6 "2920 Automedon (1981 JR)". Minor Planet Center. https://www.minorplanetcenter.net/db_search/show_object?object_id=2920. 
  2. ↑ Jump up to: 2.0 2.1 2.2 2.3 "JPL Small-Body Database Browser: 2920 Automedon (1981 JR)". Jet Propulsion Laboratory. https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2002920. 
  3. ↑ Jump up to: 3.0 3.1 3.2 3.3 3.4 3.5 3.6 "LCDB Data for (2920) Automedon". Asteroid Lightcurve Database (LCDB). http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=2920%7CAutomedon. 
  4. ↑ "List of Jupiter Trojans". Minor Planet Center. 2 February 2018. https://www.minorplanetcenter.net/iau/lists/JupiterTrojans.html. 
  5. ↑ Jump up to: 5.0 5.1 5.2 "Asteroid (2920) Automedon". AstDyS-2, Asteroids – Dynamic Site. https://newton.spacedys.com/astdys/index.php?n=2920&pc=1.1.6. 
  6. ↑ Noah Webster (1884) A Practical Dictionary of the English Language
  7. ↑ Jump up to: 7.0 7.1 7.2 7.3 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)
  8. ↑ Jump up to: 8.0 8.1 8.2 8.3 Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System – IRAS-A-FPA-3-RDR-IMPS-V6.0: IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode: 2004PDSS...12.....T. https://sbnarchive.psi.edu/pds3/iras/IRAS_A_FPA_3_RDR_IMPS_V6_0/data/diamalb.tab. Retrieved 15 June 2018. 
  9. ↑ Jump up to: 9.0 9.1 9.2 9.3 Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan 63 (5): 1117–1138. doi:10.1093/pasj/63.5.1117. Bibcode: 2011PASJ...63.1117U.  (online, AcuA catalog p. 153)
  10. ↑ Jump up to: 10.0 10.1 Molnar, Lawrence A.; Haegert, Melissa, J.; Hoogeboom, Kathleen M. (June 2008). "Lightcurve Analysis of an Unbiased Sample of Trojan Asteroids". The Minor Planet Bulletin 35 (2): 82–84. ISSN 1052-8091. Bibcode: 2008MPBu...35...82M. 
  11. ↑ Jump up to: 11.0 11.1 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. doi:10.1088/0004-6256/141/5/170. Bibcode: 2011AJ....141..170M. 
  12. ↑ Jump up to: 12.0 12.1 Stephens, Robert D.; Warner, Brian D. (October 2017). "Lightcurve Analysis of L4 Trojan Asteroids at the Center for Solar System Studies 2017 April-June". The Minor Planet Bulletin 44 (4): 312–316. ISSN 1052-8091. Bibcode: 2017MPBu...44..312S. 
  13. ↑ Jump up to: 13.0 13.1 13.2 "Asteroid 2920 Automedon". Small Bodies Data Ferret. https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=2920+Automedon. 
  14. ↑ Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus 261: 34–47. doi:10.1016/j.icarus.2015.08.007. Bibcode: 2015Icar..261...34V. 
  15. ↑ "MPC/MPO/MPS Archive". Minor Planet Center. https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html. 

External links



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