| Discovery[1] | |
|---|---|
| Discovered by | C. S. Shoemaker E. M. Shoemaker |
| Discovery site | Palomar Obs. |
| Discovery date | 10 October 1988 |
| Designations | |
| (5638) Deikoon | |
| Pronunciation | /diːˈɪkoʊɒn/[2] |
Named after | ΔηικόωνDēikoōn[1] (Greek mythology) |
| 1988 TA3 · 1988 RJ1 1989 TO2 | |
| Jupiter trojan[1][3] Trojan[4] · background[5] | |
| Orbital characteristics[3] | |
| Epoch 23 March 2018 (JD 2458200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 29.43yr (10,751 d) |
| Aphelion | 5.8119AU |
| Perihelion | 4.6861 AU |
| 5.2490 AU | |
| Eccentricity | 0.1072 |
| 12.03 yr (4,392 d) | |
| 260.33° | |
| 0° 4m 55.2s / day | |
| Inclination | 10.908° |
| 156.02° | |
| 91.817° | |
| Jupiter MOID | 0.1902 AU |
| TJupiter | 2.9520 |
| Physical characteristics | |
| 41.45±0.48 km[6] 44.22 km(calculated)[7] 63.33±3.32 km[8] | |
| 19.40±0.01 h[9] | |
| 0.044±0.005[8] 0.057(assumed)[7] 0.071±0.010[6] | |
| D(Pan-STARRS)[7][10] D(SDSS-MOC)[11][12] B–V =0.730±0.060[13] V–R =0.430±0.040[13] V–I =0.910±0.041[7] | |
| 10.00[8] 10.4[6] 10.5[1][3][7] | |
5638 Deikoon/diːˈɪkoʊɒn/ is a mid-sizedJupiter trojan from theTrojan camp, approximately 44 kilometers (27 miles) in diameter. It was discovered on 10 October 1988 by American astronomer coupleCarolyn andEugene Shoemaker at thePalomar Observatory in California.[1] The dark and possibly sphericalD-type asteroid has arotation period of 19.4 hours.[7] It was named after the Trojan heroDeicoon from Greek mythology.[1]
Deikoon is a darkJupiter trojan in a 1:1orbital resonance with Jupiter. It is located in the traileringTrojan camp at the Gas Giant'sL5Lagrangian point, 60° behind its orbit(seeTrojans in astronomy).[4] It is also a non-family asteroid of theJovian background population.[5]
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 aneccentricity of 0.11 and aninclination of 11° with respect to theecliptic.[3] The body'sobservation arc begins with aprecovery taken at Palomar in August 1988, just two months prior to its official discovery observation.[1]
Deikoon is a darkD-type asteroid, the most commonspectral type among the Jupiter trojans, according to theSDSS-based taxonomy and the survey conducted byPan-STARRS.[7][10][11][12] It has a typicalV–I color index of 0.91.[7]
In February 1994, a rotationallightcurve ofDeikoon was obtained from six nights ofphotometric observations byStefano Mottola and Anders Erikson using theESO 1-metre telescope at theLa Silla Observatory in Chile. The irregular lightcurve showed arotation period of19.40±0.01 hours and a low brightness variation of 0.07magnitude (U=2-).[7][14]
In March 2007, a refined period of19.40±0.01 hours with an amplitude of 0.14 magnitude was obtained byLawrence Molnar atCalvin College, remotely operating the 0.4-meter telescope at theCalvin-Rehoboth Robotic Observatory in New Mexico (U=2).[7][9] A low brightness amplitude is indicative of a spherical rather than elongated shape.
According to the surveys carried out by theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer and the JapaneseAkari satellite,Deikoon measures 41.45 and 63.33 kilometers in diameter and its surface has analbedo of 0.071 and 0.044, respectively.[6][8] TheCollaborative Asteroid Lightcurve Link assumes a standard albedo for acarbonaceous asteroid of 0.057 and calculates a diameter of 44.22 kilometers based on anabsolute magnitude of 10.5.[7]
Thisminor planet was named fromGreek mythology after the Trojan heroDeicoon, son ofPergasos and a friend ofAeneas. During theTrojan War, Deicoon was killed byAgamemnon's spear penetrating his shield.[1] The official naming citation was published by theMinor Planet Center on 12 July 1995 (M.P.C. 25444).[15]
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