1020 Arcadia

1020 Arcadia
Discovery
Discovered by	K. Reinmuth
Discovery site	Heidelberg Obs.
Discovery date	7 March 1924
Designations
MPC designation	(1020) Arcadia
Pronunciation	/ɑːrˈkeɪdiə/
Named after	Arcadia (Greek region)
Alternative designations	1924 QV · 1954 UA2; 1975 EQ · 1977 QO2
Minor planet category	main-belt · (middle); Agnia
Orbital characteristics
	Epoch 23 March 2018 (JD 2458200.5)
	Uncertainty parameter 0
Observation arc	93.89 yr (34,293 d)
Aphelion	2.9152 AU
Perihelion	2.6666 AU
Semi-major axis	2.7909 AU
Eccentricity	0.0445
Orbital period (sidereal)	4.66 yr (1,703 d)
Mean anomaly	18.189°
Mean motion	0° 12m 41.04s / day
Inclination	4.0598°
Longitude of ascending node	180.71°
Argument of perihelion	37.691°
Physical characteristics
Mean diameter	10.067±0.090 km; 10.415±0.123 km; 13.02±0.49 km; 21.16 km (calculated)
Synodic rotation period	17.02±0.02 h
Geometric albedo	0.057 (assumed); 0.150±0.023; 0.2364±0.0456
Spectral type	SMASS = S · S; S(SDSS-MFB)
Absolute magnitude (H)	12.0 · 12.10; 12.29±0.11

1020 Arcadia, provisional designation 1924 QV, is a stony Agnia asteroid from the central regions of the asteroid belt, approximately 11 kilometers (7 miles) in diameter. It was discovered on 7 March 1924, by German astronomer Karl Reinmuth at the Heidelberg Observatory in Heidelberg, Germany.^[1] The asteroid was named after the Greek region of Arcadia.^[3]

Orbit and classification

Arcadia is a member of the Agnia family (514),^[5]^[6] a very large family of stony asteroids with more than 2000 known members.^[13] They most likely formed from the breakup of a basalt object, which in turn was spawned from a larger parent body that underwent igneous differentiation.^[6] The family's parent body and namesake is the asteroid 847 Agnia.^[13]

It orbits the Sun in the central main-belt at a distance of 2.7–2.9 AU once every 4 years and 8 months (1,703 days; semi-major axis of 2.79 AU). Its orbit has an eccentricity of 0.04 and an inclination of 4° with respect to the ecliptic.^[4] The body's observation arc begins at Heidelberg in March 1924, six days after its official discovery observation.^[1]

Physical characteristics

In the SMASS classification, Arcadia is a common, stony S-type asteroid.^[4] It has been characterized as an S-type by Pan-STARRS photometric survey,^[12] as well as by SDSS-MFB (Masi Foglia Bus).^[10]

Rotation period

In November 2011, a fragmentary rotational lightcurve of Arcadia was obtained from photometric observations by Gordon Gartrelle at the University of North Dakota. Lightcurve analysis gave a rotation period of 17.02 hours with a brightness amplitude of 0.05 magnitude (U=1).^[11] As of 2018, no secure period has been obtained.^[10]

Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Arcadia measures between 10.067 and 13.02 kilometers in diameter and its surface has an albedo between 0.150 and 0.2364.^[7]^[8]^[9] The Collaborative Asteroid Lightcurve Link assumes an albedo 0.057, i.e. an albedo for a carbonaceous rather than for a stony asteroid, and consequently calculates a much larger diameter of 21.16 kilometers based on an absolute magnitude of 12.1.^[10] It may be speculated whether this anomaly is a glitch in the data base.

Naming

This minor planet was named after the Greek region of Arcadia in central Peloponnese. It is also a celebrated mythological region, where the shepherd god Pan lived. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 97).^[3]