9000 Hal, provisional designation , is a stony background

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

and slow rotator from the inner regions of the asteroid belt, approximately in diameter. It was discovered on 3 May 1981, by American astronomer

Edward Bowell Edward L. G. "Ted" Bowell (born 1943 in London), is an American astronomer. Bowell was educated at Emanuel School London, University College, London, and the University of Paris. He was principal investigator of the Lowell Observatory Near-Earth ...

at Lowell's

Anderson Mesa Station Anderson Mesa Station is an astronomical observatory established in 1959 as a dark-sky observing site for Lowell Observatory. It is located at Anderson Mesa in Coconino County, Arizona, about 12 miles southeast of Lowell's main campus on Mars ...

near Flagstaff, Arizona, in the United States. The likely elongated

S-type asteroid S-type asteroids are asteroids with a spectral type that is indicative of a siliceous (i.e. stony) mineralogical composition, hence the name. They have relatively high density. Approximately 17% of asteroids are of this type, making it the second ...

has an exceptionally long

rotation period The rotation period of a celestial object (e.g., star, gas giant, planet, moon, asteroid) may refer to its sidereal rotation period, i.e. the time that the object takes to complete a single revolution around its axis of rotation relative to the ...

of 908 hours. It was named after the homicidal supercomputer HAL 9000, featured in the 1968 film '' 2001: A Space Odyssey''.

Orbit and classification

''Hal'' is a non-

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

asteroid of the main belt's background population when applying the hierarchical clustering method to its

proper orbital elements __NOTOC__ The proper orbital elements or proper elements of an orbit are constants of motion of an object in space that remain practically unchanged over an astronomically long timescale. The term is usually used to describe the three quantitie ...

. Based on osculating Keplerian

orbital elements Orbital elements are the parameters required to uniquely identify a specific orbit. In celestial mechanics these elements are considered in two-body systems using a Kepler orbit. There are many different ways to mathematically describe the same ...

, the asteroid has also been classified as a member of the Flora family (), a giant

asteroid family An asteroid family is a population of asteroids that share similar proper orbital elements, such as semimajor axis, eccentricity, and orbital inclination. The members of the families are thought to be fragments of past asteroid collisions. An a ...

and the largest family of stony asteroids in the main-belt. ''Hal'' orbits the Sun in the

inner Interior may refer to: Arts and media * ''Interior'' (Degas) (also known as ''The Rape''), painting by Edgar Degas * ''Interior'' (play), 1895 play by Belgian playwright Maurice Maeterlinck * ''The Interior'' (novel), by Lisa See * Interior de ...

asteroid belt at a distance of 1.8–2.7 AU once every 3 years and 4 months (1,216 days;

semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the long ...

of 2.23 AU). Its orbit has an eccentricity of 0.21 and an

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a Plane of reference, reference plane and the orbital plane or Axis of rotation, axis of direction of the orbiting object ...

of 6 ° with respect to the ecliptic. The asteroid was first observed as at

Crimea–Nauchnij The Crimean Astrophysical Observatory (CrAO, obs. code: 095) is located at Nauchnij research campus, near the Central Crimean city of Bakhchysarai, on the Crimean peninsula. CrAO is often called simply by its location and campus name, ...

in November 1975. The body's

observation arc In observational astronomy, the observation arc (or arc length) of a Solar System body is the time period between its earliest and latest observations, used for tracing the body's path. It is usually given in days or years. The term is mostly use ...

begins with its official discovery observation at Anderson Mesa in May 1981.

Physical characteristics

''Hal'' is an assumed stony

, based on the ''Collaborative Asteroid Lightcurve Link'' (CALL) classification into the Flora family.

Rotation period

In August 2008, a rotational lightcurve of ''Hal'' was obtained from photometric observations by Slovak astronomers

Adrián Galád Adrián Galád (born 1970) is a Slovak astronomer and a discoverer of minor planets. He is credited by the Minor Planet Center with the discovery and co-discovery of 81 numbered minor planets between 1995 and 2009, most of them in collaboratio ...

, Jozef Világi,

Leonard Kornoš Leonard Kornoš (born 1956) is a Slovakia, Slovak astronomer and a prolific discoverer of asteroids. Career He is a lecturer at Comenius University in Bratislava, Slovakia, and known for his astrometric and Photometry (astronomy), photometric ...

and

Štefan Gajdoš This is a list of minor-planet discoverers credited by the Minor Planet Center with the discovery of one or several minor planets (such as near-Earth and main-belt asteroids, Jupiter trojans and distant objects). , the discovery of 612,011 numb ...

at Modra Observatory. Lightcurve analysis gave an exceptionally long

of 908 hours with a high brightness variation of 0.9 magnitude (). 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. The result, however, is considered of poor quality by CALL ().

Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's

Wide-field Infrared Survey Explorer Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and SMEX-6) is a NASA infrared astronomy space telescope in the Explorers Program. It was launched in December 2009, and placed in hibernation mode in February 2011, ...

, ''Hal'' measures between 3.61 and 4.134 kilometers in diameter and its surface has an

albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...

between 0.26 and 0.375. CALL assumes an albedo of 0.24 – derived from

8 Flora Flora (minor planet designation: 8 Flora) is a large, bright main-belt asteroid. It is the innermost ''large'' asteroid: no asteroid closer to the Sun has a diameter above 25 kilometres (20% that of Flora), and not until 20-km 149 Medusa was dis ...

, the Flora family's

parent body In meteoritics, a parent body is the celestial body from which originates a meteorite or a class of meteorites. Identification The easiest way to correlate a meteorite with a parent body is when the parent body still exists. This is the case fo ...

– and calculates a diameter of 4.11 kilometers based on an

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse Logarithmic scale, logarithmic Magnitude (astronomy), astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent mag ...

of 14.1.

Naming

This

minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...

was named after the fictional supercomputer

Hal 9000 HAL 9000 is a fictional artificial intelligence character and the main antagonist in Arthur C. Clarke's ''Space Odyssey'' series. First appearing in the 1968 film '' 2001: A Space Odyssey'', HAL ( Heuristically programmed ALgorithmic computer ...

, featured in both

Arthur C. Clarke Sir Arthur Charles Clarke (16 December 191719 March 2008) was an English science-fiction writer, science writer, futurist, inventor, undersea explorer, and television series host. He co-wrote the screenplay for the 1968 film '' 2001: A Spac ...

's novel and

Stanley Kubrick Stanley Kubrick (; July 26, 1928 – March 7, 1999) was an American film director, producer, screenwriter, and photographer. Widely considered one of the greatest filmmakers of all time, his films, almost all of which are adaptations of nove ...

's movie '' 2001: A Space Odyssey'' (1968). HAL stands for ''Heuristically programmed Algorithmic computer''. It is one of the best-known

artificial intelligence Artificial intelligence (AI) is intelligence—perceiving, synthesizing, and inferring information—demonstrated by machines, as opposed to intelligence displayed by animals and humans. Example tasks in which this is done include speech re ...

characters in modern movies. The official naming citation was published by the

Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Function ...

on 4 May 1999 (). The asteroid 4923 Clarke and 10221 Kubrick were named after the writer and movie director, respectively.

References

External links

Asteroid Lightcurve Database (LCDB)
query form

)
Dictionary of Minor Planet Names
Google books

– Observatoire de Genève, Raoul Behrend

– Minor Planet Center * * {{DEFAULTSORT:Hal 009000 Discoveries by Edward L. G. Bowell Named minor planets 009000 19810503