9000 Hal
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 homicidal supercomputer HAL 9000, featured in the 1968 film 2001: A Space Odyssey.[1]
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 supercomputer Hal 9000, featured in both Arthur C. Clarke's novel and Stanley Kubrick's movie 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 movie director, respectively.
References
- ^ a b c d e f g "9000 Hal (1981 JO)". Minor Planet Center. Retrieved 16 May 2018.
- ^ a b c d "JPL Small-Body Database Browser: 9000 Hal (1981 JO)" (2017-05-01 last obs.). Jet Propulsion Laboratory. Retrieved 16 May 2018.
- ^ a b "Asteroid 9000 Hal". Small Bodies Data Ferret. Retrieved 15 May 2018.
- ^ a b c d e f g h i j "LCDB Data for (9000) Hal". Asteroid Lightcurve Database (LCDB). Retrieved 16 May 2018.
- ^ a b c d Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63.
- ^ a b c Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Dailey, J.; et al. (November 2011). "Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters". The Astrophysical Journal. 741 (2): 20. arXiv:1109.4096. Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68. S2CID 118745497.
- ^ a b c d Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. S2CID 35447010. (catalog)
- ^ a b Behrend, Raoul. "Asteroids and comets rotation curves – (9000) Hal". Geneva Observatory. Retrieved 16 May 2018.
- ^ a b Galad, Adrian; Vilagi, Jozef; Kornos, Leonard; Gajdos, Stefan (July 2009). "Relative Photometry of Nine Asteroids from Modra". The Minor Planet Bulletin. 36 (3): 116–118. Bibcode:2009MPBu...36..116G. ISSN 1052-8091.
- ^ Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. S2CID 53493339.
- ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 16 May 2018.
External links
- Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
- Dictionary of Minor Planet Names, Google books
- Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
- Discovery Circumstances: Numbered Minor Planets (5001)-(10000) – Minor Planet Center
- 9000 Hal at AstDyS-2, Asteroids—Dynamic Site
- Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
- 9000 Hal at the JPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters
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