1919 Clemence, provisional designation , is a bright Hungaria

asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...

and suspected tumbler from the inner regions of the

asteroid belt The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids ...

, approximately 4 kilometers in diameter. It was discovered on 16 September 1971, by American astronomer James Gibson together with Argentine astronomer

Carlos Cesco Carlos Ulrrico Cesco (died 1987) was an Argentina, Argentine astronomer. He lived most of his life in San Juan, Argentina. He was a well-known discoverer of minor planets credited by the Minor Planet Center (MPC) with the discovery of 19 numbered ...

at the Yale-Columbia Southern Station at

Leoncito Astronomical Complex The El Leoncito Astronomical Complex (Spanish: Complejo Astronómico El Leoncito - CASLEO) is an astronomical observatory in the San Juan Province of Argentina. CASLEO is one of two observatories located within El Leoncito National Park, which i ...

in Argentina. It is named after astronomer Gerald Clemence.

Orbit and classification

''Clemence'' is a member of the

Hungaria family The Hungaria family (003) is a collisional asteroid family of at least 2,966 known asteroids, named for its largest member, the -across asteroid 434 Hungaria. It lies within the larger dynamical group of Hungaria asteroids, a group of asteroids ...

, which form the innermost dense concentration of asteroids in the Solar System. It orbits the Sun at a distance of 1.8–2.1 AU once every 2 years and 8 months (984 days). Its orbit has an

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-Centre (geometry), center, in geometry * Eccentricity (g ...

of 0.10 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 reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

of 19 ° with respect to the

ecliptic The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. Fr ...

Physical characteristics

In the

Tholen Tholen () is a 25,000 people municipality in the southwest of the Netherlands. The municipality of Tholen takes its name from the town of Tholen, which is the largest population center in the municipality. The municipality consists of two peninsu ...

taxonomic scheme, ''Clemence'' is classified as an

X-type asteroid The X-group of asteroids collects together several types with similar spectra, but probably quite different compositions. Tholen classification In the Tholen classification, the X-group consists of the following types: * E-type – with high ...

. It has also been characterized as an

E-type asteroid E-type (enstatite achondrite–type) asteroids are asteroids thought to have enstatite (MgSiO3) achondrite surfaces. They form a large proportion of asteroids inward of the asteroid belt known as Hungaria asteroids, but rapidly become very ...

by the

NEOWISE Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy space telescope in the Explorers Program launched in December 2009.. . WISE discovered thousands of minor planets and nu ...

mission.

Rotation period

In March 2005, a rotational

lightcurve In astronomy, a light curve is a graph (discrete mathematics), graph of the Radiance, light intensity of a celestial object or region as a function of time, typically with the magnitude (astronomy), magnitude of light received on the ''y''-axis ...

was obtained by American astronomer Brian Warner at his Palmer Divide Observatory () in Colorado. Lightcurve analysis gave a

rotation period In astronomy, the rotation period or spin period of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the '' sidereal rotation period'' (or ''sidereal day''), i.e., the time that the objec ...

of hours and a brightness variation of

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

(). While not being a slow rotator, ''Clemence'' has a significantly longer period than most other asteroids, which typically have a spin rate between 2 and 20 hours. Czech astronomer

Petr Pravec Petr Pravec (born September 17, 1967) is a Czech astronomer and a discoverer of minor planets, born in Třinec, Czech Republic. Pravec is a prolific discoverer of binary asteroids, expert in photometric observations and rotational lightcurves ...

from the

Ondřejov Observatory The Ondřejov Observatory (; ) is the principal observatory of the Astronomical Institute of the Czech Academy of Sciences. It is located in the municipality of Ondřejov, southeast of Prague, Czech Republic. It has a wide telescope, which i ...

believes this may be a tumbling asteroid, yet observations are not sufficient to determine a non-principal axis rotation.

Diameter and albedo

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

Wide-field Infrared Survey Explorer Wide-field Infrared Survey Explorer (WISE, List of observatory codes, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy Space observatory, space telescope in the Explorers Program launched in December 2009.. . WISE L ...

, the asteroid measures 3.2 kilometers in diameter and its surface has an outstandingly high

albedo Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...

of 0.71, while the ''Collaborative Asteroid Lightcurve Link'' assumes an albedo of 0.30 and calculates a somewhat larger diameter of 4.95 kilometers with an absolute magnitude of 13.45.

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 American astronomer

Gerald Maurice Clemence Gerald Maurice Clemence (16 August 1908 – 22 November 1974) was an American astronomer. Inspired by the life and work of Simon Newcomb, his career paralleled the huge advances in astronomy brought about by the advent of the electronic computer. C ...

(1908–1974), first scientific director of the

United States Naval Observatory The United States Naval Observatory (USNO) is a scientific and military facility that produces geopositioning, navigation and timekeeping data for the United States Navy and the United States Department of Defense. Established in 1830 as the ...

and professor of astronomy at the Yale Observatory, known for his work on the theory of the motion of Mars and Mercury, on the system of astronomical constants, and other research in

celestial mechanics Celestial mechanics is the branch of astronomy that deals with the motions of objects in outer space. Historically, celestial mechanics applies principles of physics (classical mechanics) to astronomical objects, such as stars and planets, to ...

. He served as president of the

American Astronomical Society The American Astronomical Society (AAS, sometimes spoken as "double-A-S") is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC. The primary objective of the AAS is to promote the adv ...

and of

IAU The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

. The official 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. Funct ...

on 20 February 1976 ().

Orbit and classification

Physical characteristics

Rotation period

Diameter and albedo

Naming

References

External links