1215 Boyer, provisional designation , is a stony Eunomian

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. ...

from the central region of the

asteroid belt The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, c ...

, approximately 20 kilometers in diameter. It was discovered by astronomer Alfred Schmitt in 1932, who named it after French astronomer and college Louis Boyer.

Discovery

''Boyer'' was discovered on 19 January 1932, by French astronomer Alfred Schmitt at the

Algiers Observatory The Algiers Observatory was built in the late 19th century in the Algiers suburb of Bouzaréah, Algeria, North Africa. It participated in the Astrographic Catalogue project, taking the zone between -2 and +4 degrees to expose 1,260 plates between ...

in Algeria, North Africa. Eight days later, it was independently discovered by

Karl Reinmuth Karl Wilhelm Reinmuth (4 April 1892 in Heidelberg – 6 May 1979 in Heidelberg) was a German astronomer and a prolific discoverer of 395 minor planets. Scientific career From 1912 to 1957, Reinmuth was working as an astronomer at the Hei ...

Heidelberg Observatory Heidelberg (; Palatine German: ') is a city in the German state of Baden-Württemberg, situated on the river Neckar in south-west Germany. As of the 2016 census, its population was 159,914, of which roughly a quarter consisted of student ...

in Germany. 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 at Algiers with its official discovery observation.

Classification and orbit

''Boyer'' is a member of the

Eunomia family The Eunomia or Eunomian family () is a large asteroid family of S-type asteroids named after the asteroid 15 Eunomia. It is the most prominent family in the intermediate asteroid belt and the 6th-largest family with nearly six thousand known members ...

(), the most prominent family in the intermediate main-belt, which mostly consists of stony asteroids. Conversely, ''Boyer'' has also been grouped into the

Maria family The Maria family (adj. ''Marian''; FIN: 506; also known as ''Roma family'') is a collisional asteroid family located in the inner parts of the intermediate asteroid belt, near the 1:3 Kirkwood gap. The family consist of several thousand stony S-ty ...

(). It orbits the Sun at a distance of 2.2–2.9 AU once every 4 years and 2 months (1,512 days). Its orbit has an eccentricity of 0.13 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 Ea ...

of 16 ° with respect to the

ecliptic The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic agains ...

Physical characteristics

In the

Tholen 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 differentiated ...

, ''Boyer'' is a common, stony

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 secon ...

Lightcurves

In August 2008 and May 2012, two rotational

lightcurve In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular freq ...

s of ''Boyer'' were obtained from photometric observations by an international collaboration of astronomers studying the rotational properties of Maria asteroids, using the ground-based

Wise Observatory The Florence and George Wise Observatory (IAU code 097) is an astronomical observatory owned and operated by Tel Aviv University. It is located west of the town of Mitzpe Ramon in the Negev desert near the edge of the Ramon Crater, and it is ...

in Israel. Lightcurve analysis gave 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 10.36 hours with a brightness variation of 0.31 and 050 magnitude, respectively ().

Diameter and albedo

According to the surveys carried out by the Japanese Akari satellite and 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 2 ...

with its subsequent

NEOWISE 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 201 ...

mission, ''Boyer'' measures between 13.041 and 24.65 kilometers in diameter and its surface has an

albedo Albedo (; ) is the measure of the diffuse reflection of 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 that refle ...

between 0.116 and 0.3012. The ''Collaborative Asteroid Lightcurve Link'' assumes an albedo of 0.21, derived from the Eunomia family's largest member and namesake, 15 Eunomia, and calculates a diameter of 17.47 kilometers with an

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it ...

of 11.1.

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 by the discoverer after his colleague at Algiers Observatory, Louis Boyer (1901–1999), who worked extensively on asteroids and

comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ...

s. Boyer himself was a

discoverer of minor planets 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 nu ...

at Algiers. He later worked on identifications at Nice observatory. 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 T ...

on 1 August 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:Boyer 001215 Discoveries by Alfred Schmitt Named minor planets 001215 19320119