5638 Deikoon

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5638 Deikoon
Discovery [1]
Discovered byC. S. Shoemaker
E. M. Shoemaker
Discovery sitePalomar Obs.
Discovery date10 October 1988
MPC designation(5638) Deikoon
Named after
(Greek mythology)
1988 TA3 · 1988 RJ1
1989 TO2
Jupiter trojan[1][2]
Trojan[3] · background[4]
Orbital characteristics[2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc29.43 yr (10,751 d)
Aphelion5.8119 AU
Perihelion4.6861 AU
5.2490 AU
12.03 yr (4,392 d)
0° 4m 55.2s / day
Jupiter MOID0.1902 AU
Physical characteristics
Mean diameter
41.45±0.48 km[5]
44.22 km (calculated)[6]
63.33±3.32 km[7]
19.40±0.01 h[8]
0.057 (assumed)[6]
D (Pan-STARRS)[6][9]
D (SDSS-MOC)[10][11]
B–V = 0.730±0.060[12]
V–R = 0.430±0.040[12]
V–I = 0.910±0.041[6]

5638 Deikoon, provisional designation 1988 TA3, is a mid-sized Jupiter trojan from the Trojan camp, approximately 44 kilometers (27 miles) in diameter. It was discovered on 10 October 1988 by American astronomer couple Carolyn and Eugene Shoemaker at the Palomar Observatory in California.[1] The dark and possibly spherical D-type asteroid has a rotation period of 19.4 hours.[6] It was named after the Trojan hero Deicoon from Greek mythology.[1]

Orbit and classification[edit]

Deikoon is a dark Jupiter trojan 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 (see Trojans in astronomy).[3] It is also a non-family asteroid of the Jovian background population.[4]

It orbits the Sun at a distance of 4.7–5.8 AU once every 12.03 years (4,392 days; semi-major axis of 5.25 AU). Its orbit has an eccentricity of 0.11 and an inclination of 11° with respect to the ecliptic.[2] The body's observation arc begins with a precovery taken at Palomar in August 1988, just two months prior to its official discovery observation.[1]

Physical characteristics[edit]

Deikoon is a dark D-type asteroid, the most common spectral type among the Jupiter trojans, according to the SDSS-based taxonomy and the survey conducted by Pan-STARRS.[6][9][10][11] It has a typical V–I color index of 0.91.[6]

Rotation period[edit]

In February 1994, a rotational lightcurve of Deikoon was obtained from six nights of photometric observations by Stefano Mottola and Anders Erikson using the ESO 1-metre telescope at the La Silla Observatory in Chile. The irregular lightcurve showed a rotation period of 19.40±0.01 hours and a low brightness variation of 0.07 magnitude (U=2-).[6][13]

In March 2007, a refined period of 19.40±0.01 hours with an amplitude of 0.14 magnitude was obtained by Lawrence Molnar at Calvin College, remotely operating the 0.4-meter telescope at the Calvin-Rehoboth Robotic Observatory in New Mexico (U=2).[6][8] A low brightness amplitude is indicative of a spherical rather than elongated shape.

Diameter and albedo[edit]

According to the surveys carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer and the Japanese Akari satellite, Deikoon measures 41.45 and 63.33 kilometers in diameter and its surface has an albedo of 0.071 and 0.044, respectively.[5][7] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for a carbonaceous asteroid of 0.057 and calculates a diameter of 44.22 kilometers based on an absolute magnitude of 10.5.[6]


This minor planet was named from Greek mythology after the Trojan hero Deicoon, son of Pergasos and a friend of Aeneas. During the Trojan War, Deicoon was killed by Agamemnon's spear penetrating his shield.[1] The official naming citation was published by the Minor Planet Center on 12 July 1995 (M.P.C. 25444).[14]


  1. ^ a b c d e f g h "5638 Deikoon (1988 TA3)". Minor Planet Center. Retrieved 22 June 2018.
  2. ^ a b c d "JPL Small-Body Database Browser: 5638 Deikoon (1988 TA3)" (2018-01-24 last obs.). Jet Propulsion Laboratory. Retrieved 22 June 2018.
  3. ^ a b "List of Jupiter Trojans". Minor Planet Center. 1 June 2018. Retrieved 22 June 2018.
  4. ^ a b "Asteroid (5638) Deikoon – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 22 June 2018.
  5. ^ a b c d 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 22 June 2018. (online catalog)
  6. ^ a b c d e f g h i j k "LCDB Data for (5638) Deikoon". Asteroid Lightcurve Database (LCDB). Retrieved 22 June 2018.
  7. ^ a b c d 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. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. Retrieved 22 June 2018. (online, AcuA catalog p. 153)
  8. ^ a b 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. Bibcode:2008MPBu...35...82M. ISSN 1052-8091. Retrieved 22 June 2018.
  9. ^ a b 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" (PDF). Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 22 June 2018.
  10. ^ a b 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 22 June 2018.
  11. ^ a b "Asteroid 5638 Deikoon". Small Bodies Data Ferret. Retrieved 22 June 2018.
  12. ^ a b 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. Retrieved 22 June 2016.
  13. ^ 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. Retrieved 22 June 2018.
  14. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 22 June 2018.

External links[edit]