Astronomy:9000 Hal

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9000 Hal
Discovery [1]
Discovered byE. Bowell
Discovery siteAnderson Mesa Stn.
Discovery date3 May 1981
Designations
(9000) Hal
Pronunciation/ˈhæl/
Named afterHAL 9000 [1]
(Fictional supercomputer)
1981 JO · 1975 VH3
1981 JJ3 · 1995 US3
Minor planet categorymain-belt [1][2] · (inner)
background [3] · Flora [4]
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc41.49 yr (15,156 d)
|{{{apsis}}}|helion}}2.6955 AU
|{{{apsis}}}|helion}}1.7648 AU
2.2301 AU
Eccentricity0.2087
Orbital period3.33 yr (1,216 d)
Mean anomaly328.38°
Mean motion0° 17m 45.24s / day
Inclination6.2618°
Longitude of ascending node226.61°
79.871°
Physical characteristics
Mean diameter3.61±0.78 km[5]
4.11 km (calculated)[4]
4.134±0.935 km[6][7]
Rotation period22.68±0.02 h (poor)[8]
908 h[9]
Geometric albedo0.24 (assumed)[4]
0.26±0.13[5]
0.375±0.184[6][7]
S (assumed)[4]
Absolute magnitude (H)13.6[7]
14.0[2]
14.1[4]
14.35±0.66[10]
14.42[5]


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 ({{{1}}}). 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 ({{{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

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 "9000 Hal (1981 JO)". Minor Planet Center. https://www.minorplanetcenter.net/db_search/show_object?object_id=9000. 
  2. ↑ 2.0 2.1 2.2 2.3 "JPL Small-Body Database Browser: 9000 Hal (1981 JO)". Jet Propulsion Laboratory. https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009000. 
  3. ↑ 3.0 3.1 "Asteroid 9000 Hal". Small Bodies Data Ferret. https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=9000%20Hal. 
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 "LCDB Data for (9000) Hal". Asteroid Lightcurve Database (LCDB). http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=9000%7CHal. 
  5. ↑ 5.0 5.1 5.2 5.3 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. doi:10.3847/0004-6256/152/3/63. Bibcode: 2016AJ....152...63N. 
  6. ↑ 6.0 6.1 6.2 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. doi:10.1088/0004-637X/741/2/68. Bibcode: 2011ApJ...741...68M. 
  7. ↑ 7.0 7.1 7.2 7.3 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. doi:10.1088/0004-637X/741/2/90. Bibcode: 2011ApJ...741...90M.  (catalog)
  8. ↑ 8.0 8.1 Behrend, Raoul. "Asteroids and comets rotation curves – (9000) Hal". Geneva Observatory. http://obswww.unige.ch/~behrend/page5cou.html#009000. 
  9. ↑ 9.0 9.1 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. ISSN 1052-8091. Bibcode: 2009MPBu...36..116G. 
  10. ↑ 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. doi:10.1016/j.icarus.2015.08.007. Bibcode: 2015Icar..261...34V. 
  11. ↑ "MPC/MPO/MPS Archive". Minor Planet Center. https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html. 

External links



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