1303 Luthera, provisional designation , is a dark

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 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 (orbit), eccentricity, and orbital inclination. The members of the families are thought to be Collisional family, fra ...

, located in the outermost 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 ...

. It measures approximately 90 kilometers in diameter. The asteroid was discovered on 16 March 1928, by astronomer Friedrich Schwassmann at the Bergedorf Observatory in Hamburg, Germany, and later named after German astronomer Robert Luther.

Orbit and classification

''Luthera'' is the parent body 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. An ...

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 longe ...

of 3.23 AU). 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 ...

. 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 fo ...

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 (; ; ) is the List of cities in Baden-Württemberg by population, fifth-largest city in the States of Germany, German state of Baden-Württemberg, and with a population of about 163,000, of which roughly a quarter consists of studen ...

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 (astronomy), phase angle) to that of an ''idealized'' flat, fully reflecting, diffuse reflection, d ...

, ''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 the ...

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 (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 ...

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 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 5.878 hours with a low brightness variation of 0.05

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 ...

, 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 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 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 ...

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

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 ...

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 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 ''minor ...

was named after German astronomer

Karl Theodor Robert Luther Karl Theodor Robert Luther (16 April 1822, Świdnica – 15 February 1900 Düsseldorf), normally published as Robert Luther, was a German astronomer. While working at the Bilk Observatory in Düsseldorf, Germany, he searched for asteroids and di ...

(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'' 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