1218 Aster

1218 Aster, provisional designation 1932 BJ, is a bright asteroid from the inner regions of the asteroid belt, approximately 5.5 kilometers in diameter. Discovered by Karl Reinmuth in 1932, it was later named after the flowering plant Aster.

1218 Aster

Shape model of Aster from its lightcurve
Discovery[1]
Discovered by	K. Reinmuth
Discovery site	Heidelberg Obs.
Discovery date	29 January 1932
Designations
MPC designation	(1218) Aster
Pronunciation	/ˈæstər/[2]
Named after	Aster (genus of flowers)[3]
Alternative designations	1932 BJ · 1978 TJ5 1978 VQ12
Minor planet category	main-belt · (inner)
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	85.35 yr (31,173 days)
Aphelion	2.5110 AU
Perihelion	2.0158 AU
Semi-major axis	2.2634 AU
Eccentricity	0.1094
Orbital period (sidereal)	3.41 yr (1,244 days)
Mean anomaly	56.714°
Mean motion	0° 17m 21.84s / day
Inclination	3.1572°
Longitude of ascending node	63.820°
Argument of perihelion	69.372°
Physical characteristics
Dimensions	5.554±0.084 km[4]
Geometric albedo	0.332±0.043[4]
Absolute magnitude (H)	13.2[1]

Discovery

Aster was discovered on 29 January 1932, by German astronomer Karl Reinmuth at Heidelberg Observatory in southern Germany.^[5] Two nights later, it was independently discovered by Italian astronomer Mario A. Ferrero at the Pino Torinese Observatory at Turin, Italy.^[3]

Classification and orbit

Aster orbits the Sun in the inner main-belt at a distance of 2.0–2.5 AU once every 3 years and 5 months (1,244 days). Its orbit has an eccentricity of 0.11 and an inclination of 3° with respect to the ecliptic.^[1]

The asteroid's observation arc begins at the discovering observatory, one week after its official discovery observation.^[5]

Physical characteristics

Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Aster measures 5.554 kilometers in diameter and its surface has an albedo of 0.332.^[4]

Lightcurves

As of 2017, rotational lightcurve of Aster has been obtained.^[6] The body's rotation period, shape and variation in magnitude shifted from unknown movements^[1][7] to specific identifiable spin/shape determinations.

Naming

The minor planet was named after the genus of flowers, Aster (also see List of minor planets named after animals and plants § Plants). The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 113).^[3]