It orbits the Sun at a distance of 4.7–5.8 AU once every 11 years and 11 months (4,354 days; semi-major axis of 5.22 AU). Its orbit has an eccentricity of 0.10 and an inclination of 17° with respect to the ecliptic.[4] The body's observation arc begins with its official discovery observation at Heidelberg in October 1930.[1]
In July and August 2008, Susan Lederer at CTIO in Chile, and Robert Stephens at the Goat Mountain Astronomical Research Station (G79) in California, determined a well-defined period of 8.705±0.005 h with an amplitude 0.20 magnitude (U=3).[5][14] Follow-up observations during 2015–2017 by Robert Stephens and Daniel Coley at the Center for Solar System Studies gave three concurring periods of 8.701, 8.681 and 8.7 hours with an amplitude of 0.62, 0.40 and 0.21 magnitude, respectively (U=3/3/3),[11][12][13][a] while in August 2011, Pierre Antonini reported a period of 11.8 hours based on a fragmentary lightcurve (U=2-).[19]
Diameter and albedo
According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Äneas measures between 118.02 and 148.66 kilometers in diameter – making it anywhere from the 8th to 4th largest Jupiter trojan – determined from a common absolute magnitude of 8.33 and a surface albedo between 0.037 and 0.059.[8][9][10] The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0403 and a diameter of 142.82 kilometers based on an absolute magnitude of 8.33.[5]
100+ largest Jupiter trojans
Largest Jupiter Trojans by survey(A) (mean-diameter in kilometers; YoD: Year of Discovery)
Note: missing data was completed with figures from the JPL SBDB (query) and from the LCDB (query form) for the WISE/NEOWISE and SIMPS catalogs, respectively. These figures are given in italics. Also, listing is incomplete above #100.
Spectral type
In the Tholen and Barucci classification, Äneas is a dark D-type asteroid, while in the Tedesco classification is as D/P-type asteroid. Its high V–I color index of 0.99 is typical for D-types.[16]
Notes
^ abcdLightcurve plots of (1172) Äneas from Jan 2015, Jan 2016 and Dec 2016 (n.a.) by Daniel Coley and Robert Stephens at the Center for Solar System Studies (U80) and (U81). Quality code is 3/3/3 (lightcurve rating at CS3). Summary figures at the LCDB and CS3.
^ abcdTedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System – IRAS-A-FPA-3-RDR-IMPS-V6.0: IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 15 June 2018.
^ abcdUsui, 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. (online, AcuA catalog p. 153)