1404 Ajax

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1404 Ajax
Discovery [1]
Discovered by K. Reinmuth
Discovery site Heidelberg Obs.
Discovery date 17 August 1936
MPC designation (1404) Ajax
Pronunciation /ˈæks/ AY-jaks
Named after
Ajax (Greek mythology)[2]
1936 QW
Jupiter trojan[1]
(Greek camp)[3]
Orbital characteristics[1]
Epoch 16 February 2017 (JD 2457800.5)
Uncertainty parameter 0
Observation arc 79.77 yr (29,135 days)
Aphelion|Aphelion 5.9024 AU
Perihelion|Perihelion 4.7036 AU
5.3030 AU
Eccentricity 0.1130
12.21 yr (4,461 days)
0° 4m 50.52s / day
Inclination 18.003°
Jupiter MOID 0.0414 AU
Jupiter Tisserand parameter 2.8890
Physical characteristics
Dimensions 81.43 km (derived)[4]
81.69±3.2 km[5]
83.990±1.279 km[6][7]
96.34±2.25 km[8]
28.4 h[9]
29.38±0.01 h[10]
34 h[11]
0.0508 (derived)[4]
9.00[5][8] · 9.3[1][4][6] · 9.87±0.47[12]

1404 Ajax (/ˈæks/ AY-jaks), provisional designation 1936 QW, is a carbonaceous Jupiter trojan from the Greek camp, approximately 82 kilometers in diameter. It was discovered on 17 August 1936, by German astronomer Karl Reinmuth at Heidelberg Observatory in southern Germany, and named after Ajax from Greek mythology.[13]

Orbit and classification[edit]

Ajax is a C-type asteroid, that orbits in the leading Greek camp at Jupiter's L4 Lagrangian point, 60° ahead of its orbit (see Trojans in astronomy). Jupiter trojans are thought to have been captured into their orbits during or shortly after the early stages of the formation of the Solar System. More than 4,000 Jupiter trojans in the Greek camp have already been discovered.[3]

It orbits the Sun at a distance of 4.7–5.9 AU once every 12 years and 3 months (4,461 days). Its orbit has an eccentricity of 0.11 and an inclination of 18° with respect to the ecliptic.[1] The body's observation arc begins at Heidelberg 6 days after its official discovery observations, with no precoveries taken, and no prior identifications made.[13]

Physical characteristics[edit]

Rotation period[edit]

In December 2010, a rotational lightcurve of Ajax was obtained from photometric observations taken at the Chilean CTIO and at the Goat Mountain Astronomical Research Station (G79). Lightcurve analysis gave a rotation period of 29.38 hours with a brightness variation of 0.30 magnitude (U=3-).[10] Previous observations by Richard P. Binzel in 1988, and by Roberto Crippa and Federico Manzini in 2009, gave a period of 28.4 and 34 hours, respectively (U=1/2-).[9][11]

Diameter and albedo[edit]

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Ajax measures between 81.69 and 96.34 kilometers in diameter, and its surface has an albedo between 0.048 and 0.067.[5][6][7][8] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0508 and a diameter of 81.43 kilometers with an absolute magnitude of 9.3.[4]


This minor planet was named for Ajax the Great, a Greek warrior of great strength and courage in the Trojan War. He is the half brother of Teucer and son of king Telamon, who kills himself because Achilles' armor was awarded to Odysseus. The Jupiter trojans 588 Achilles, 1143 Odysseus and 1749 Telamon and 2797 Teucer are all named after these figures from Greek mythology.[2] Naming of Ajax was first cited in The Names of the Minor Planets by Paul Herget in 1955 (H 127).[2]


  1. ^ a b c d e "JPL Small-Body Database Browser: 1404 Ajax (1936 QW)" (2016-05-24 last obs.). Jet Propulsion Laboratory. Retrieved 11 January 2017. 
  2. ^ a b c Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (1404) Ajax. Springer Berlin Heidelberg. p. 113. ISBN 978-3-540-00238-3. Retrieved 11 January 2017. 
  3. ^ a b "List of Jupiter Trojans". Minor Planet Center. 20 June 2016. Retrieved 27 December 2016. 
  4. ^ a b c d e "LCDB Data for (1404) Ajax". Asteroid Lightcurve Database (LCDB). Retrieved 11 January 2017. 
  5. ^ a b c d Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System. Bibcode:2004PDSS...12.....T. Retrieved 11 January 2017. 
  6. ^ a b c d Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results" (PDF). The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407Freely accessible. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. Retrieved 11 January 2017. 
  7. ^ 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:1209.1549Freely accessible. Bibcode:2012ApJ...759...49G. doi:10.1088/0004-637X/759/1/49. Retrieved 11 January 2017. 
  8. ^ 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 11 January 2017. 
  9. ^ a b Binzel, Richard P.; Sauter, Linda M. (February 1992). "Trojan, Hilda, and Cybele asteroids – New lightcurve observations and analysis". Icarus: 222–238. Bibcode:1992Icar...95..222B. doi:10.1016/0019-1035(92)90039-A. ISSN 0019-1035. Retrieved 11 January 2017. 
  10. ^ a b French, Linda M.; Stephens, Robert D.; Lederer, Susan M.; Coley, Daniel R.; Rohl, Derrick A. (April 2011). "Preliminary Results from a Study of Trojan Asteroids". The Minor Planet Bulletin. 38 (2): 116–120. Bibcode:2011MPBu...38..116F. ISSN 1052-8091. Retrieved 11 January 2017. 
  11. ^ a b Behrend, Raoul. "Asteroids and comets rotation curves – (1404) Ajax". Geneva Observatory. Retrieved 11 January 2017. 
  12. ^ 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. arXiv:1506.00762Freely accessible. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 11 January 2017. 
  13. ^ a b "1404 Ajax (1936 QW)". Minor Planet Center. Retrieved 11 January 2017. 

External links[edit]