1303 Luthera, provisional designation , is a dark

asteroid An asteroid is a minor planet of the Solar System#Inner solar system, 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 o ...

and the parent body of the

Luthera 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. A ...

, located in the outermost regions 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, called ...

. It measures approximately 90 kilometers in diameter. The asteroid was discovered on 16 March 1928, by astronomer

Friedrich Schwassmann Friedrich Karl Arnold Schwassmann (25 March 1870 – 19 January 1964) was a German astronomer and a discoverer of 22 minor planets and 4 comets, who worked at AOP in Potsdam and at Bergedorf Observatory in Hamburg. He was co-discoverer with ...

at the Bergedorf Observatory in Hamburg, Germany, and later named after German astronomer Robert Luther.

Orbit and classification

''Luthera'' is the

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 ...

of the

(), a smaller

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. A ...

of less than 200 known members. It orbits the Sun in the outermost asteroid belt at a distance of 2.9–3.6 AU once every 5 years and 10 months (2,120 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 lo ...

of 3.23 AU). Its orbit has an eccentricity 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 Plane of reference, reference plane and the orbital plane or Axis of rotation, axis of direction of the orbiting object ...

of 19 ° 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 agai ...

. The asteroid was first observed as at

Simeiz Observatory Simeiz Observatory (also spelled Simeis or Simeïs) was an astronomy research observatory until the mid-1950s. It is located on Mount Koshka, Crimea, , by the town of Simeiz. Part of the Crimean Astrophysical Observatory, it is currently used for ...

in May 2017. 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

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 students. ...

in April 1928, or one month after its official discovery observation at Bergedorf.

Physical characteristics

Due to its low

geometric albedo In astronomy, the geometric albedo of a celestial body is the ratio of its actual brightness as seen from the light source (i.e. at zero phase angle) to that of an ''idealized'' flat, fully reflecting, diffusively scattering ( Lambertian) disk w ...

, ''Luthera'' is an assumed carbonaceous

C-type asteroid C-type (carbonaceous) asteroids are the most common variety, forming around 75% of known asteroids. They are volatile-rich and distinguished by a very low albedo because their composition includes a large amount of carbon, in addition to rocks ...

, while the overall

spectral type In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting th ...

for members of the

is that of an X-type.

Rotation period

In February 2008, a 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 frequ ...

of ''Luthera'' was obtained from photometric observations by Mexican astronomer Pedro Sada at the University of Monterrey, Mexico. Lightcurve analysis gave a short

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 5.878 hours with a low brightness variation of 0.05 magnitude, indicative for a nearly spherical shape (). A lower-rated lightcurve with a period of 7.92 hours and an amplitude of 0.06 magnitude was obtained by French amateur astronomer Pierre Antonini in May 2009 ().

Diameter and albedo

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

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 20 ...

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 2 ...

, ''Luthera'' measures between 81.685 and 112.74 kilometers in diameter and its surface has a low

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 refl ...

between 0.024 and 0.059. The ''Collaborative Asteroid Lightcurve Link'' derives an albedo of 0.0387 and a diameter of 85.08 kilometers based on 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 we ...

of 9.5.

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 '' ...

was named after German astronomer Karl Theodor Robert Luther (1822–1900), who was a discoverer of minor planets himself, most notably 17 Thetis, 90 Antiope ( binary) and 288 Glauke ( slow rotator). The official naming citation was mentioned in ''

The Names of the Minor Planets Paul Herget (January 30, 1908 – August 27, 1981) was an American astronomer and director of the Cincinnati Observatory, who established the Minor Planet Center after World War II. Career Herget taught astronomy at the University of Cincinn ...

'' by Paul Herget in 1955 (). The lunar crater '' Luther'' has also been named after him.

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:Luthera 001303 Discoveries by Friedrich Karl Arnold Schwassmann Named minor planets 19280316