645 Agrippina

645 Agrippina

Discovery
Discovered by	J. H. Metcalf
Discovery site	Taunton, MA, USA
Discovery date	13 September 1907
Designations
MPC designation	645 Agrippina
Named after	Agrippina (the Elder, the Younger)
Alternative names	1907 AG
Minor planet category	main-belt (outer)
Orbital characteristics
Epoch 27 June 2015 (JD 2457200.5)
Uncertainty parameter 0
Observation arc	108.19 yr (39,515 days)
Aphelion	3.6821 AU
Perihelion	2.7436 AU
Semi-major axis	3.2128 AU
Eccentricity	0.1460
Orbital period	5.76 yr (2,103 days)
Mean anomaly	254.02°
Inclination	7.0432°
Longitude of ascending node	0.1676°
Argument of perihelion	84.203°
Physical characteristics
Dimensions	28.00±1.3 km (IRAS:17) 30.86±0.76 km 36.165±0.406 km 29.57±0.58 km 27.94 km (derived)
Rotation period	32.6 h 34.39±0.05 h
Geometric albedo	0.2381±0.025 (IRAS:17) 0.198±0.011 0.1369±0.0218 0.213±0.028 0.2283 (SIMPS)
Spectral type	B–V = 0.871 U–B = 0.412 Tholen = S · S
Absolute magnitude (H)	9.94

645 Agrippina, provisional designation 1907 AG, is a stony asteroid from the outer region of the asteroid belt, roughly 30 kilometers in diameter. It was discovered by American astronomer reverend Joel Metcalf at Taunton, Massachusetts, USA, on 13 September 1907.

The S-type asteroid orbits the Sun at a distance of 2.7–3.7 AU once every 5 years and 9 months (2,103 days). Its orbit shows an eccentricity of 0.15 and is tilted by 7 degrees to the plane of the ecliptic. A photometric light-curve analysis from the 1980s and a provisional observation in 2004 rendered a rotation period of 32.6 and 34.4 hours, respectively.

According to the surveys carried out by the Infrared Astronomical Satellite, IRAS, the Japanese Akari satellite, and the U.S.Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, the asteroid has a dissimilar albedo in the range of 0.14 to 0.23, which leads to a varying estimate for its diameter from 28 to 36 kilometers. The Collaborative Asteroid Lightcurve Link publishes an albedo of 0.23 from an alternative result of the Supplemental IRAS Minor Planet Survey (SIMPS) and derives a slightly lower diameter of 27.9 kilometers.

The minor planet was named for two women of ancient Roman history. Agrippina the Elder (14 BCE – 33) was the daughter of the Roman statesman Marcus Vipsanius Agrippa, the wife of Germanicus and the mother of the Emperor Caligula. Her daughter, Agrippina the Younger (15–59 AD) was the mother of Emperor Nero. The naming might be influenced by the two letters of the provisional designation 1907 AG. In the Dictionary of Minor Planet Names, Lutz Schmadel supposes that the name originated from a list of female names from mythology and history, compiled by the Astronomisches Rechen-Institut (ARI) in 1913. The ARI then sent this list to a number of astronomers with the request to name their discoveries in order to avoid confusion, as the number of unnamed minor planet up to number 700 had grown significantly at the time.

External links

• Asteroid Lightcurve Database (LCDB), query form (info)
• Dictionary of Minor Planet Names, Google books
• Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
• Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
• 645 Agrippina at the JPL Small-Body Database

• Discovery · Orbit diagram · Orbital elements · Physical parameters