11351 Leucus

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11351 Leucus
Discovery [1]
Discovered by SCAP
Discovery site Beijing Xinglong Obs.
Discovery date 12 October 1997
MPC designation (11351) Leucus
Pronunciation /ˈljkəs/
Named after
Leucus (Greek mythology)[2]
1997 TS25 · 1996 VP39
Jupiter trojan[2]
(Greek camp)[3]
Orbital characteristics[1]
Epoch 16 February 2017 (JD 2457800.5)
Uncertainty parameter 0
Observation arc 20.57 yr (7,515 days)
Aphelion 5.6204 AU
Perihelion 4.9497 AU
5.2851 AU
Eccentricity 0.0635
12.15 yr (4,438 days)
0° 4m 51.96s / day
Inclination 11.558°
Jupiter MOID 0.1006 AU
TJupiter 2.9550
Physical characteristics
Dimensions 34.155±0.646[4]
34.16±0.65 km[5]
42.07 km (derived)[6]
42.16±4.0 km (IRAS:2)[1]
440 h[7]
513.7±1.3 h[8][a]
0.0524 (derived)[6]
0.0627±0.014 (IRAS:2)[1]
B–V = 0.739±0.044[9]
V–R = 0.498±0.044[9]
V–I = 0.900±0.057[9]
10.7[1][5][6] · 11.38±0.00[10]

11351 Leucus (/ˈljkəs/), provisional designation 1997 TS25, is a dark Jupiter trojan and an exceptionally slow rotator, approximately 42 kilometers in diameter. It is a target of the Lucy mission, scheduled for a fly by in April 2028.[11][12]

This asteroid was discovered on 12 October 1997, by the Beijing Schmidt CCD Asteroid Program (SCAP) at Xinglong Station in the Chinese province of Hebei, and later named after Leucus from Greek mythology.[2]

Orbit and classification[edit]

Leucus is a carbonaceous C-type asteroid that is located in the Greek camp of Jupiter's leading L4 Lagrangian point. It orbits the Sun at a distance of 4.9–5.6 AU once every 12 years and 2 months (4,438 days). Its orbit has an eccentricity of 0.06 and an inclination of 12° with respect to the ecliptic.[1] The first precovery was taken at Siding Spring Observatory in 1982, extending the asteroid's observation arc by 15 years prior to its official discovery at Xinglong.[2]

Physical characteristics[edit]

Slow rotator[edit]

During spring 2013, a rotational lightcurve of Leucus was obtained from photometric observations made by astronomers Robert Stephens and Daniel Coley at the Center for Solar System Studies (CS3), California, using a 0.35/0.4-meter Schmidt-Cassegrain telescope. The lightcurve showed an exceptionally slow rotation period of 513.7 hours with a brightness variation of 0.53 in magnitude (U=2+). No evidence of a non-principal axis rotation (NPAR) was found,[8][a] it is one of the slowest rotators known to exist.

In preparation for the planned visit by the Lucy spacecraft, Leucus was once again observed by astronomers Marc Buie at SwRI and Stefano Mottola at DLR in 2016. The obtained bimodal lightcurve gave a somewhat shorter period of 440 hours and an amplitude of 0.7 magnitude.[7]

Diameter and albedo[edit]

According to the surveys carried out by the Infrared Astronomical Satellite, IRAS, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, the body has a low albedo of 0.06 and 0.08, with a diameter of 42.1 and 34.2 kilometers, respectively.[4][5] The Collaborative Asteroid Lightcurve Link derives a lower albedo of 0.05 and a diameter of 42.1 kilometers, in accordance with the result obtained by IRAS.[6]


This minor planet was named from Greek mythology, after the Achaean warrior Leucus in Homer's Iliad. He was a companion of Odysseus.[2] Leucus was killed during the Trojan War by Antiphus, one of the fifty sons of King Priam of Troy,[13] the approved naming citation was published by the Minor Planet Center on 22 February 2016 (M.P.C. 98711).[14]

Lucy mission target[edit]

Leucus is planned to be visited by the Lucy spacecraft which will launch in 2021. The fly by is scheduled for 18 April 2028, and will approach the asteroid to a distance of 1000 kilometers at a velocity of 5.9 kilometers per second.[11] The mission's targets with their flyby dates are:[11][12][15]

  1. 52246 Donaldjohanson — 20 April 2025: 4 km diameter C-type asteroid in the inner main-belt, member of ~130Myr old Erigone family;
  2. 3548 Eurybates — 12 August 2027: 64 km diameter C-type Jupiter Trojan in the Greek camp at L4, largest member of the only confirmed disruptive collisional family in the Trojans;
  3. 15094 Polymele — 15 September 2027: 21 km diameter P-type Trojan at L4, likely collisional fragment;
  4. 11351 Leucus — 18 April 2028: 34 km diameter D-type slow rotator Trojan at L4;
  5. 21900 Orus — 11 November 2028: 51 km diameter D-type Trojan at L4;
  6. 617 Patroclus — 2 March 2033: P-type binary Trojan. The primary, Patroclus, has a mean diameter of 113 km and its companion, Menoetius, has a diameter of 104 km. The pair orbit at a separation of 680 km. The binary resides in the Trojan camp at L5.


  1. ^ a b lightcurve plot of 11351 Leucus by Daniel Coley at the Center for Solar System Studies from 29 March to 1 May 2013, giving a period of 513.7±1.3 hours. Quality code of 2


  1. ^ a b c d e f "JPL Small-Body Database Browser: 11351 Leucus (1997 TS25)" (2017-06-07 last obs.). Jet Propulsion Laboratory. Retrieved 5 July 2017. 
  2. ^ a b c d e "11351 Leucus (1997 TS25)". Minor Planet Center. Retrieved 26 May 2016. 
  3. ^ "List of Jupiter Trojans". Minor Planet Center. 20 June 2016. Retrieved 4 December 2016. 
  4. ^ 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 5 December 2016. 
  5. ^ 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". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407Freely accessible. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. Retrieved 26 May 2016. 
  6. ^ a b c d e "LCDB Data for (11351) Leucus". Asteroid Lightcurve Database (LCDB). Retrieved 26 May 2016. 
  7. ^ a b Buie, Marc W.; Zangari, Amanda Marie; Marchi, Simone; Mottola, Stefano; Levison, Harold F. (October 2016). "Ground-based characterization of Leucus and Polymele, two fly-by targets of the Lucy Discovery mission". American Astronomical Society. Bibcode:2016DPS....4820806B. Retrieved 13 April 2017. 
  8. ^ a b French, Linda M.; Stephens, Robert, D.; Coley, Daniel R.; Wasserman, Lawrence H.; Vilas, Faith; La Rocca, Daniel (October 2013). "A Troop of Trojans: Photometry of 24 Jovian Trojan Asteroids" (PDF). The Minor Planet Bulletin. 40 (4): 198–203. Bibcode:2013MPBu...40..198F. ISSN 1052-8091. Retrieved 26 May 2016. 
  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:1209.1896Freely accessible. Bibcode:2012A&A...546A.115H. doi:10.1051/0004-6361/201219566. Retrieved 26 May 2016. 
  10. ^ 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 26 May 2016. 
  11. ^ a b c Levison, H. F.; Olkin, C.; Noll, K. S.; Marchi, S.; Lucy Team (March 2017). "Lucy: Surveying the Diversity of the Trojan Asteroids: The Fossils of Planet Formation" (PDF). 48th Lunar and Planetary Science Conference. Bibcode:2017LPI....48.2025L. Retrieved 13 April 2017. 
  12. ^ a b Casey Dreier; Emily Lakdawalla (30 September 2015). "NASA announces five Discovery proposals selected for further study". The Planetary Society. Retrieved 12 April 2017. 
  13. ^ Homer, Iliad, 4. 491
  14. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 26 May 2016. 
  15. ^ https://www.hou.usra.edu/meetings/lpsc2017/pdf/2025.pdf

External links[edit]