5130 Ilioneus

Shape model of Ilioneus from its lightcurve
Discovery [1]
Discovered by	C. Shoemaker
Discovery site	Palomar Obs.
Discovery date	30 September 1989
Designations
MPC designation	(5130) Ilioneus
Pronunciation	/ɪliˈoʊniːəs, ɪˈlaɪənjuːs/[2]
Named after	Ἰλιονεύς Īlioneys[1] (Greek mythology)
Alternative designations	1989 SC7 · 1990 VE8
Minor planet category	Jupiter trojan [1][3] Trojan [4] · background [5]
Adjectives	Ilione(i)an
Orbital characteristics [3]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc	62.45 yr (22,810 d)
Aphelion	5.2617 AU
Perihelion	5.1571 AU
Semi-major axis	5.2094 AU
Eccentricity	0.0100
Orbital period (sidereal)	11.89 yr (4,343 d)
Mean anomaly	154.90°
Mean motion	0° 4m 58.44s / day
Inclination	15.739°
Longitude of ascending node	242.53°
Argument of perihelion	104.54°
Jupiter MOID	0.1347 AU
TJupiter	2.9250
Physical characteristics
Mean diameter	52.49±3.94 km[6] 59.40±5.4 km[7] 60.71±0.98 km[8]
Synodic rotation period	14.768±0.014 h[9]
Geometric albedo	0.0602±0.013[7] 0.069±0.013[8] 0.077±0.012[6]
Spectral type	C (assumed)[10] B–V = 0.940±0.060[11] V–R = 0.390±0.040[11] V–I = 0.960±0.030[10]
Absolute magnitude (H)	9.6[8] 9.7[1][3] 9.80[10][6][7]

5130 Ilioneus /ɪliˈoʊniːəs/ is a dark Jupiter trojan from the Trojan camp, approximately 60 kilometers (37 miles) in diameter. It was discovered on 30 September 1989, by American astronomer Carolyn Shoemaker at the Palomar Observatory in California.^[1] The assumed C-type asteroid belongs to the 70 largest Jupiter trojans and has a rotation period of 14.8 hours.^[10] It was named after Ilioneus from Greek mythology.^[1]

Orbit and classification

Ilioneus is a dark Jovian asteroid orbiting in the trailering Trojan camp at Jupiter's L₅ Lagrangian point, 60° behind on the Gas Giant's orbit in a 1:1 resonance (see Trojans in astronomy). It is also a non-family asteroid of the Jovian background population.^[5]

It orbits the Sun at a distance of 5.2–5.3 AU once every 11 years and 11 months (4,343 days; semi-major axis of 5.21 AU). Its orbit has an eccentricity of 0.01 and an inclination of 16° with respect to the ecliptic.^[3] The body's observation arc begins with a precovery taken at Palomar in December 1955, almost 34 years prior to its official discovery observation.^[1]

Naming

This minor planet was named by the discover from Greek mythology after Ilioneus, a ship commander and official spokesman under Aeneas.^[1] The official naming citation was published by the Minor Planet Center on 4 June 1993 (M.P.C. 22249).^[12]

Physical characteristics

Ilioneus is an assumed C-type asteroid. Its V–I color index of 0.96 is typical for most D-type asteroids, the dominant spectral type among the Jupiter trojans.^[10]

Rotation period

Photometric observations of Ilioneus were obtained by Stefano Mottola in February 1994. Lightcurve analysis gave a rotation period of 14.768±0.014 hours with a brightness amplitude of 0.16 magnitude (U=3).^[10][9]

Follow-up observations by astronomers at the Palomar Transient Factory in 2013, and by Robert D. Stephens at the Center for Solar System Studies in 2015 and 2017, gave a concurring period determination with an amplitude between 0.18 and 0.34 (U=2/3/3).^{[10][13][14][15][a]}

Diameter and albedo

According to the surveys carried out by the Japanese Akari satellite, the Infrared Astronomical Satellite IRAS, and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Ilioneus measures between 52.49 and 60.71 kilometers in diameter and its surface has an albedo between 0.060 and 0.077.^[6][7][8] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0602 and a diameter of 59.40 kilometers based on an absolute magnitude of 9.8.^[10]