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 aneccentricity of 0.10 and aninclination of 17° with respect to theecliptic.[4] The body'sobservation arc begins with its official discovery observation at Heidelberg in October 1930.[1]
In July and August 2008, Susan Lederer atCTIO in Chile, andRobert Stephens at the Goat Mountain Astronomical Research Station (G79) in California, determined a well-defined period of8.705±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 theCenter 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]
According to the surveys carried out by the Infrared Astronomical SatelliteIRAS, the JapaneseAkari satellite and theNEOWISE mission of NASA'sWide-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 commonabsolute magnitude of 8.33 and a surfacealbedo between 0.037 and 0.059.[8][9][10] TheCollaborative 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.
In theTholen and Barucci classification,Äneas is a darkD-type asteroid, while in the Tedesco classification is asD/P-type asteroid. Its highV–I color index of 0.99 is typical for D-types.[16]
^abcdLightcurve plots of (1172) Äneas fromJan 2015,Jan 2016 andDec 2016 (n.a.) by Daniel Coley andRobert Stephens at the Center for Solar System Studies (U80) and (U81). Quality code is 3/3/3 (lightcurve rating at CS3). Summary figures at theLCDB andCS3.
^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)