2099 Öpik, provisional designation , is a dark and eccentric

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 Mars-crosser from the inner regions of the asteroid belt, approximately 5.1 kilometers in diameter. The asteroid was discovered on 8 November 1977, by American astronomer

Eleanor Helin Eleanor Francis "Glo" Helin (née Francis, 19 November 1932 – 25 January 2009) was an American astronomer. She was principal investigator of the Near-Earth Asteroid Tracking (NEAT) program of NASA's Jet Propulsion Laboratory. (Some sources gi ...

at the

Palomar Observatory Palomar Observatory is an astronomical research observatory in San Diego County, California, United States, in the Palomar Mountain Range. It is owned and operated by the California Institute of Technology (Caltech). Research time at the observat ...

in California, and named after Estonian astronomer

Ernst Öpik Ernst Julius Öpik ( – 10 September 1985) was an Estonian astronomer and astrophysicist who spent the second half of his career (1948–1981) at the Armagh Observatory in Northern Ireland. Education Öpik was born in Kunda, Estonia, Kunda, Lä ...

Orbit and classification

''Öpik'' 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 ...

main-belt at a distance of 1.5–3.1 AU once every 3 years and 6 months (1,277 days). Its orbit has an eccentricity of 0.36 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 27 ° with respect to the ecliptic. The first used

precovery In astronomy, precovery (short for pre-discovery recovery) is the process of finding the image of an object in images or photographic plates predating its discovery, typically for the purpose of calculating a more accurate orbit. This happens mos ...

was taken at the discovering observatory in 1970, extending the asteroid'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 ...

by 7 years prior to its discovery.

Physical characteristics

Originally, the asteroid's spectral type was that of a bright

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 ...

in the Tholen classification. More recently, it has been characterized as a dark Ch-type, a hydrated subtype of the carbonaceous C-type asteroids in the

SMASS classification An asteroid spectral type is assigned to asteroids based on their emission spectrum, color, and sometimes albedo. These types are thought to correspond to an asteroid's surface composition. For small bodies that are not internally differentiat ...

, which is in agreement with its low

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 ...

(below).

Diameter and albedo

According to the survey carried out by 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, ...

with its subsequent NEOWISE mission, ''Öpik'' measures 5.17 kilometers in diameter and its surface has an

of 0.05. The ''Collaborative Asteroid Lightcurve Link'' assumes a standard albedo for carbonaceous asteroids of 0.057 and calculates a diameter of 5.12 kilometers with 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 15.18.

Rotation period

In 2005, a photometric lightcurve analysis by several astronomers including Pierre Antonini, rendered a

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 hours and with a brightness amplitude of 0.21 in magnitude (), superseding the results of an observation from the 1990s that gave a longer period of 9.3 hours ().

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 Estonian astronomer and astrophysicist,

(1893–1985), who has influenced many fields of astronomy during his 60-year long career. He is noted for developing the discipline of ''statistical

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 ...

'' and for methods to estimate the lifetimes of planet-crossing asteroids. In the early 1950s, he calculated the impact probability of Mars-crossing asteroids with Mars, and concluded that a search for impact craters on Mars would be a fruitful. Fourteen years later, Martian craters were discovered by Mariner 4. 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. Function ...

on 1 November 1978 ().

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:Opik 002099 Discoveries by Eleanor F. Helin Named minor planets 002099 002099 19771108