2000 Herschel

2000 Herschel, provisional designation 1960 OA, is a stony Phocaea asteroid and a tumbling slow rotator from the inner regions of the asteroid belt, approximately 16 kilometers (10 miles) in diameter. It was discovered 29 July 1960, by German astronomer Joachim Schubart at Sonneberg Observatory in eastern Germany.^[1] The S-type asteroid has a long rotation period of 130 hours.^[5] It was named after astronomer William Herschel.^[3]

2000 Herschel

Discovery[1]
Discovered by	J. Schubart
Discovery site	Sonneberg Obs.
Discovery date	29 July 1960
Designations
MPC designation	(2000) Herschel
Pronunciation	/ˈhɜːrʃəl/[2]
Named after	William Herschel[3] (German-British astronomer)
Alternative designations	1960 OA · 1934 NX
Minor planet category	main-belt[1][4] · (inner)[5] Phocaea[6]
Orbital characteristics[4]
Epoch 27 April 2019 (JD 2458600.5)
Uncertainty parameter 0
Observation arc	84.08 yr (30,712 d)
Aphelion	3.0885 AU
Perihelion	1.6708 AU
Semi-major axis	2.3796 AU
Eccentricity	0.2979
Orbital period (sidereal)	3.67 yr (1,341 d)
Mean anomaly	293.69°
Mean motion	0° 16m 6.6s / day
Inclination	22.819°
Longitude of ascending node	291.92°
Argument of perihelion	130.51°
Physical characteristics
Mean diameter	14.768±0.348 km[7][8] 16.15±3.11 km[9] 16.86±1.17 km[10] 17.385±0.173 km[11]
Synodic rotation period	130±2 h[5][12]
Geometric albedo	0.1870[11] 0.197[10] 0.24[9] 0.256[7][8]
Spectral type	Tholen = S[4][5] B–V = 0.893[4] U–B = 0.494[4]
Absolute magnitude (H)	11.25[1][4][5][7][10][11] 11.42[9]

Orbit and classification

Herschel is a member of the Phocaea family (701),^[6] a large family of stony asteroids with nearly two thousand known members.^[13]: 23 It orbits the Sun in the inner main-belt at a distance of 1.7–3.1 AU once every 3 years and 8 months (1,341 days; semi-major axis of 2.38 AU). Its orbit has an eccentricity of 0.30 and an inclination of 23° with respect to the ecliptic.^[4] It was first identified as 1934 NX at Johannesburg Observatory in 1934, extending the body's observation arc by 26 years prior to its official discovery observation at Sonneberg.^[1]

The relatively high orbital eccentricity of this object causes it to come close to the orbit of the planet Mars. This means there is a chance it will eventually collide with the planet, with the odds of a collision estimated at 18% per billion orbits.^[14]

Naming

This minor planet was named in honour of the English astronomer of German origin William Herschel (1738–1822), who discovered what he called Georgium Sidus (aka Uranus). The official naming citation was published by the Minor Planet Center on 15 October 1977 (M.P.C. 4237).^[15] While the minor planet with number "1000", 1000 Piazzia, honors the discoverer of the first minor planet, Giuseppe Piazzi, number "2000" does so for Herschel, discoverer of the first telescopic major planet.^[3] The asteroid is one of several early "kilo-numbered" minor planets that were dedicated to renowned scientists or institutions including:^[16]

• 1000 Piazzia named for Giuseppe Piazzi, discoverer of Ceres
• 2000 Herschel for William Herschel who discovered Uranus
• 3000 Leonardo for the Italian polymath of the Renaissance, Leonardo da Vinci
• 4000 Hipparchus for ancient Greek astronomer Hipparchus

The sequence continues with the asteroids 5000 IAU (for the International Astronomical Union), 6000 United Nations (for the United Nations), 7000 Curie (for the pioneers on radioactivity, Marie and Pierre Curie), and 8000 Isaac Newton (for Isaac Newton),^[16] while 9000 Hal (after HAL 9000 from 2001: A Space Odyssey) and 10000 Myriostos (after the Greek word for ten-thousandth, which is meant to honor all astronomers) were named based on their direct numeric accordance.

Physical characteristics

In the Tholen classification, Herschel is a common S-type asteroid.^[4]

Slow rotator and tumbler

Analysis of the lightcurve for this object appears to show that it is tumbling, with rotation occurring about the non-principal axis. Lightcurve analysis gave a rotation period of 130±3 hours with a high brightness variation of 1.16±0.05 magnitude (U=2).^[12] This makes it a slow rotator.^[5]

Diameter and albedo

The Collaborative Asteroid Lightcurve Link assumes a standard albedo for a stony asteroid of 0.20 and calculates a diameter of 16.71 kilometers based on an absolute magnitude of 11.25.^[5] According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Herschel measures between 14.768 and 17.385 kilometers in diameter and its surface has an albedo between 0.1870 and 0.256.^{[7][8][9][10][11]}

See also

• 20000 Varuna