23 Thalia

23 Thalia (/θəˈlaɪ.ə/^[a]) is a large main-belt asteroid. It was discovered by J. R. Hind on 15 December 1852, at the private observatory of W. Bishop, located in Hyde Park, London, England.^[5] Bishop named it after Thalia, the Muse of comedy and pastoral poetry in Greek mythology.^[6]

23 Thalia

A three-dimensional model of 23 Thalia based on its light curve.
Discovery
Discovered by	J. R. Hind
Discovery date	15 December 1852
Designations
MPC designation	(23) Thalia
Pronunciation	/θəˈlaɪ.ə/[1][a]
Named after	Thalia
Alternative designations	1938 CL; 1974 QT2
Minor planet category	Main belt
Orbital characteristics
Epoch 14 June 2006 (JD 2453900.5)
Aphelion	484.663 Gm (3.240 AU)
Perihelion	301.483 Gm (2.015 AU)
Semi-major axis	393.073 Gm (2.628 AU)
Eccentricity	0.233
Orbital period (sidereal)	1555.679 d (4.26 a)
Mean anomaly	328.687°
Inclination	10.145°
Longitude of ascending node	67.228°
Argument of perihelion	59.311°
Physical characteristics
Dimensions	107.53 ± 2.2 km (IRAS)[2] 106.81 ± 3.23 km[3]
Mass	(1.96 ± 0.09) × 1018 kg[3]
Mean density	3.07 ± 0.31 g/cm3[3]
Synodic rotation period	12.312 h[2]
Geometric albedo	0.2536 (geometric)[4]
Spectral type	S[2]
Apparent magnitude	9.11 to 13.19
Absolute magnitude (H)	7.17[2]

It is categorized as an S-type asteroid consisting of mainly of iron- and magnesium-silicates. This the second most common type of asteroid in the main belt. Based on analysis of the light curve, the object has a sidereal rotation period of 0.513202 ± 0.000002 days. An ellipsoidal model of the light curve gives an a/b ratio of 1.28 ± 0.05.^[7]

With a semimajor axis of 2.628, the asteroid is orbiting between the 3:1 and 5:2 Kirkwood gaps in the main belt.^[8] Its orbital eccentricity is larger than the median value of 0.07 for the main belt, and the inclination is larger than the median of below 4°. But most of the main-belt asteroids have an eccentricity of no more than 0.4 and an inclination of up to 30°, so the orbit of 23 Thalia is not unusual for a main-belt asteroid.^[9]

Thalia has been studied by radar.^[10]

Announcement of the discovery in the Illustrated London News, Saturday 18 December 1852.

Notes

1. Stressed on the second syllable.