5244 Amphilochos


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5244 Amphilochos is a mid-sized Jupiter trojan from the Greek camp, approximately 36 kilometers (22 miles) in diameter. It was discovered at the Palomar Observatory during the second Palomar–Leiden Trojan survey in 1973, and was later named after the seer Amphilochus from Greek mythology.[1] The dark Jovian asteroid is likely elongated in shape and has a rotation period of 7.8 hours.[8]

5244 Amphilochos
Discovery [1]
Discovered byC. J. van Houten
I. van Houten-G.
T. Gehrels
Discovery sitePalomar Obs.
Discovery date29 September 1973
Designations
(5244) Amphilochos
Pronunciation[2]

Named after

Amphilochus [1]
(Greek mythology)
1973 SQ1 · 1989 AO2
Jupiter trojan [1][3]
Greek [4] · background [5]
Orbital characteristics [3]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc62.52 yr (22,836 d)
Aphelion5.3177 AU
Perihelion5.0270 AU
5.1723 AU
Eccentricity0.0281
11.76 yr (4,297 d)
318.67°
0° 5m 1.68s / day
Inclination6.1555°
213.29°
125.05°
Jupiter MOID0.1211 AU
TJupiter2.9880
Physical characteristics
36.69±0.69 km[6]
9.766±0.002 h[7][a]
0.091±0.018[6]
C (assumed)[8]
V–R = 0.407±0.044[9]
V–I = 0.770±0.047[9]
10.40[1][3]
10.509±0.007 (R)[10]
10.96[8]

Amphilochos was discovered on 29 September 1973, 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 with a precovery taken at Palomar in April 1955, more than 18 years prior to its official discovery observation.[1]

Palomar–Leiden Trojan survey

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Despite being discovered during the second Palomar–Leiden Trojan survey in 1973, Amphilochos has not received a provisional survey designation prefixed with "T-2". The survey was a fruitful collaboration between the Palomar and Leiden observatories during the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.[11]

Orbit and classification

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Amphilochos is a dark Jovian asteroid 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).[4] It is also a non-family asteroid of the Jovian background population.[5][12]

It orbits the Sun at a distance of 5.0–5.3 AU once every 11 years and 9 months (4,297 days; semi-major axis of 5.17 AU). Its orbit has an eccentricity of 0.03 and an inclination of 6° with respect to the ecliptic.[3]

This minor planet was named from Greek mythology after the seer Amphilochus, son of Amphiaraus. After the Trojan War, he was warned by a vision which saved his life as he returned to the Trojan shore before the Greek fleet departed. Amphilochus lived together with Calchas (see 4138 Kalchas) in Asia Minor. The official naming citation was published by the Minor Planet Center on 26 February 1994 (M.P.C. 23137).[13]

Physical characteristics

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Amphilochos is an assumed C-type asteroid, while the majority of larger Jupiter trojans are D-types.[8] It has an untypically low V–I color index of 0.77 (see table below).[9]

In September 2010, a first rotational lightcurve of Amphilochos was obtained from photometric observations in the R-band by astronomers at the Palomar Transient Factory. Lightcurve analysis gave a rotation period of 9.787 hours with a brightness variation of 0.51 magnitude (U=2).[10] The best-rated lightcurve with a well-defined period of 9.766±0.002 hours and a high amplitude of 0.79 magnitude was obtained by Robert Stephens at the Center for Solar System Studies in Landers, California, in May 2015. A high brightness amplitude typically indicates that the body has a non-spherical shape.[7][a]

In August 2015, observations by the Kepler space telescope during its K2 mission gave another two lightcurves with a concurring period of 9.578 and 9.797 hours with a brightness variation of 0.73 and 0.67 magnitude, respectively (U=2/2+).[14][15] The Collaborative Asteroid Lightcurve Link (CALL), labels the period determination for this asteroid as ambiguous.[8]

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Amphilochos measures 36.69 kilometers in diameter and its surface has an albedo of 0.091,[6] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for a carbonaceous asteroid of 0.057 and calculates a diameter of 35.79 kilometers based on an absolute magnitude of 10.96.[8]

  1. ^ a b Lightcurve plots of (5244) Amphilochos from May 2015 by Robert Stephens at the Center for Solar System Studies (U81). Quality code is 3 (lightcurve rating at CS3). Summary figures at the LCDB and CS3.
  1. ^ a b c d e f g "5244 Amphilochos (1973 SQ1)". Minor Planet Center. Retrieved 2 July 2018.
  2. ^ 'Amphilochus' in Noah Webster (1884) A Practical Dictionary of the English Language
  3. ^ a b c d "JPL Small-Body Database Browser: 5244 Amphilochos (1973 SQ1)" (2017-10-27 last obs.). Jet Propulsion Laboratory. Retrieved 2 July 2018.
  4. ^ a b "List of Jupiter Trojans". Minor Planet Center. 1 July 2018. Retrieved 2 July 2018.
  5. ^ a b "Asteroid (5244) Amphilochos – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 2 July 2018.
  6. ^ a b c 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. ^ a b Stephens, Robert D.; Coley, Daniel, R.; French, Linda M. (January 2016). "Large L5 Jovian Trojan Asteroid Lightcurves from the Center for Solar System Studies". The Minor Planet Bulletin. 43 (1): 15–22. Bibcode:2016MPBu...43...15S. ISSN 1052-8091.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  8. ^ a b c d e f "LCDB Data for (5244) Amphilochos". Asteroid Lightcurve Database (LCDB). Retrieved 2 July 2018.
  9. ^ a b c 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. ^ a b 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. arXiv:1504.04041. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75. S2CID 8342929.
  11. ^ "Minor Planet Discoverers". Minor Planet Center. 31 May 2018. Retrieved 21 June 2018.
  12. ^ "Asteroid 5244 Amphilochos". Small Bodies Data Ferret. Retrieved 2 July 2018.
  13. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 2 July 2018.
  14. ^ Szabó, Gy. M.; Pál, A.; Kiss, Cs.; Kiss, L. L.; Molnár, L.; Hanyecz, O.; et al. (March 2017). "The heart of the swarm: K2 photometry and rotational characteristics of 56 Jovian Trojan asteroids". Astronomy and Astrophysics. 599: 13. arXiv:1609.02760. Bibcode:2017A&A...599A..44S. doi:10.1051/0004-6361/201629401. S2CID 119275951.
  15. ^ Ryan, Erin Lee; Sharkey, Benjamin N. L.; Woodward, Charles E. (March 2017). "Trojan Asteroids in the Kepler Campaign 6 Field". The Astronomical Journal. 153 (3): 12. Bibcode:2017AJ....153..116R. doi:10.3847/1538-3881/153/3/116. S2CID 125570438.