9000 Hal
Main-belt asteroid
From Wikipedia, the free encyclopedia
9000 Hal, provisional designation 1981 JO, is a stony background asteroid and slow rotator from the inner regions of the asteroid belt, approximately 4 kilometers (2.5 miles) in diameter. It was discovered on 3 May 1981, by American astronomer Edward Bowell at Lowell's Anderson Mesa Station near Flagstaff, Arizona, in the United States.[1] The likely elongated S-type asteroid has an exceptionally long rotation period of 908 hours.[4] It was named after the fictional supercomputer HAL 9000, featured in the 1968 film 2001: A Space Odyssey.[1]
| Discovery[1] | |
|---|---|
| Discovered by | E. Bowell |
| Discovery site | Anderson Mesa Stn. |
| Discovery date | 3 May 1981 |
| Designations | |
| (9000) Hal | |
| Pronunciation | /ˈhæl/ |
Named after | HAL 9000[1] (Fictional supercomputer) |
| 1981 JO · 1975 VH3 1981 JJ3 · 1995 US3 | |
| main-belt[1][2] · (inner) background[3] · Flora[4] | |
| Orbital characteristics[2] | |
| Epoch 23 March 2018 (JD 2458200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 41.49 yr (15,156 d) |
| Aphelion | 2.6955 AU |
| Perihelion | 1.7648 AU |
| 2.2301 AU | |
| Eccentricity | 0.2087 |
| 3.33 yr (1,216 d) | |
| 328.38° | |
| 0° 17m 45.24s / day | |
| Inclination | 6.2618° |
| 226.61° | |
| 79.871° | |
| Physical characteristics | |
| 3.61±0.78 km[5] 4.11 km (calculated)[4] 4.134±0.935 km[6][7] | |
| 22.68±0.02 h (poor)[8] 908 h[9] | |
| 0.24 (assumed)[4] 0.26±0.13[5] 0.375±0.184[6][7] | |
| S (assumed)[4] | |
| 13.6[7] 14.0[2] 14.1[4] 14.35±0.66[10] 14.42[5] | |
Orbit and classification
Hal is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.[3] Based on osculating Keplerian orbital elements, the asteroid has also been classified as a member of the Flora family (402), a giant asteroid family and the largest family of stony asteroids in the main-belt.[4]
Hal orbits the Sun in the inner asteroid belt at a distance of 1.8–2.7 AU once every 3 years and 4 months (1,216 days; semi-major axis of 2.23 AU). Its orbit has an eccentricity of 0.21 and an inclination of 6° with respect to the ecliptic.[2] The asteroid was first observed as 1975 VH3 at Crimea–Nauchnij in November 1975. The body's observation arc begins with its official discovery observation at Anderson Mesa in May 1981.[1]
Physical characteristics
Hal is an assumed stony S-type asteroid, based on the Collaborative Asteroid Lightcurve Link's (CALL) classification into the Flora family.[4]
Rotation period
In August 2008, a rotational lightcurve of Hal was obtained from photometric observations by Slovak astronomers Adrián Galád, Jozef Világi, Leonard Kornoš and Štefan Gajdoš at Modra Observatory.[9] Lightcurve analysis gave an exceptionally long rotation period of 908 hours with a high brightness variation of 0.9 magnitude (U=2+). This makes Hal one of the slowest rotators known to exist. In addition, the body's high brightness amplitude is indicative of a non-spherical shape.
An alternative measurement by French amateur astronomers Pierre Antonini and René Roy gave a much shorter period of 22.68 hours.[8] The result, however, is considered of poor quality by CALL (U=1).[4]
Diameter and albedo
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Hal measures between 3.61 and 4.134 kilometers in diameter and its surface has an albedo between 0.26 and 0.375.[5][6][7] CALL assumes an albedo of 0.24 – derived from 8 Flora, the Flora family's parent body – and calculates a diameter of 4.11 kilometers based on an absolute magnitude of 14.1.[4]
Naming
This minor planet was named after the fictional and homicidal supercomputer HAL 9000, featured in both Arthur C. Clarke's novel and Stanley Kubrick's film 2001: A Space Odyssey (1968).[1] HAL stands for Heuristically programmed Algorithmic computer. It is one of the best-known artificial intelligence characters in modern movies. The official naming citation was published by the Minor Planet Center on 4 May 1999 (M.P.C. 34628).[11] The asteroid 4923 Clarke and 10221 Kubrick were named after the writer and film director, respectively.
