958 Asplinda ( ''prov. designation'': ''or'' ) is a resonant

Hilda asteroid The Hilda asteroids (adj. ''Hildian'') are a dynamical group of more than 5,000 asteroids located beyond the asteroid belt but within Jupiter's orbit, in a 3:2 orbital resonance with Jupiter. The namesake is the asteroid 153 Hilda. Hildas move i ...

, approximately in diameter, located in the outermost region of the asteroid belt. It was discovered on 28 September 1921, by astronomer

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 Lande ...

at the

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 southwest Germany. The assumed C-type asteroid has 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 16.5 hours and is likely elongated in shape. It was named after Swedish astronomer

Bror Asplind Bror is a Scandinavian masculine given name which simply means 'brother'. The name has been found as early as in runestones in the form Brodhir. The name form Bror is known since the year 1536. It is also used heavily in a colloquial sense in the ci ...

(1890–1954).

Orbit and classification

''Asplinda'' is a member of the distant orbital

Hilda group The Hilda asteroids (adj. ''Hildian'') are a dynamical group of more than 5,000 asteroids located beyond the asteroid belt but within Jupiter's orbit, in a 3:2 orbital resonance with Jupiter. The namesake is the asteroid 153 Hilda. Hildas move ...

of asteroids, which stay in a 3:2 orbital resonance with

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...

. It is however not a member of the collisional

Hilda family The Hilda asteroids (adj. ''Hildian'') are a dynamical group of more than 5,000 asteroids located beyond the asteroid belt but within Jupiter's orbit, in a 3:2 orbital resonance with Jupiter. The namesake is the asteroid 153 Hilda. Hildas move i ...

() but a non-

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

asteroid of the background population when applying the hierarchical clustering method to its

proper orbital elements __NOTOC__ The proper orbital elements or proper elements of an orbit are constants of motion of an object in space that remain practically unchanged over an astronomically long timescale. The term is usually used to describe the three quantitie ...

. It orbits the Sun in the outermost asteroid belt at a distance of 3.2–4.7 AU once every 7 years and 11 months (2,905 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 long ...

of 3.98 AU). Its orbit has an eccentricity of 0.18 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 6 ° with respect to the ecliptic. 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 on 24 October 1921, four weeks after its official discovery observation.

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

Bror Ansgar Asplind Bror is a Scandinavian masculine given name which simply means 'brother'. The name has been found as early as in runestones in the form Brodhir. The name form Bror is known since the year 1536. It is also used heavily in a colloquial sense in the c ...

(1890–1954), a Swedish astronomer and orbit computer. The following, sequentially numbered asteroids

959 Arne 959 Arne ('' prov. designation:'' ''or'' ) is a background asteroid and slow rotator, approximately in diameter, located in the outer region of the asteroid belt. It was discovered by German astronomer Karl Reinmuth at the Heidelberg-Königstu ...

960 Birgit 960 Birgit ( ''prov. designation'': ''or'' ) is a background asteroid, approximately in diameter, located in the Florian region of the inner asteroid belt. It was discovered on 1 October 1921, by astronomer Karl Reinmuth at the Heidelberg Obse ...

and

961 Gunnie 961 Gunnie ( ''prov. designation'': ''or'' ) is a very dark background asteroid from the central regions of the asteroid belt, approximately in diameter. It was discovered on 10 October 1921, by German astronomer Karl Reinmuth at the Heidelberg ...

are named after his three children, respectively. The was mentioned in '' The Names of the Minor Planets'' by Paul Herget in 1955 ().

Physical characteristics

No spectral type has been published for ''Asplinda''. As an Hildian asteroid with a low albedo ''(see below)'' it is a carbonaceous C-type asteroid (assumed), or possibly a D-type or

P-type asteroid P-type asteroids are asteroids that have low albedo and a featureless reddish spectrum. It has been suggested that they have a composition of organic rich silicates, carbon and anhydrous silicates, possibly with water ice in their interior. P-type ...

, which are very common among the Hildian and more distant

Jupiter trojan The Jupiter trojans, commonly called trojan asteroids or simply trojans, are a large group of asteroids that share the planet Jupiter's orbit around the Sun. Relative to Jupiter, each trojan librates around one of Jupiter's stable Lagrange poin ...

population.

Rotation period and poles

In December 2017, a rotational lightcurve of ''Asplinda'' was obtained from photometric observations by Brian Warner,

Robert Stephens Sir Robert Graham Stephens (14 July 193112 November 1995) was a leading English actor in the early years of Britain's Royal National Theatre. He was one of the most respected actors of his generation and was at one time regarded as the natur ...

and Daniel Coley at the

Center for Solar System Studies This is a list of observatory codes (IAU codes or MPC codes) published by the Minor Planet Center. For a detailed description, ''see observations of small Solar System bodies''. List References * {{DEFAULTSORT:Observat ...

in California. Lightcurve analysis gave a

of hours with a high brightness amplitude of magnitude, indicative of an elongated, non-spherical shape (). The results supersedes previous observations with a period determination of by the same astronomers in 2016, and a period of published by Mats Dahlgren in 1998 (). The 2017 observations by Warner, Stephens and Coley also gave two spin axes of (228.0°, 33.0°) and (46.0°, 45.0°) in ecliptic coordinates (λ, β) and a sidereal period of hours. These results supersede the asteroid's 2016 modeled spin axes and lightcurve with a sidereal period of hours based on data from the Uppsala Asteroid Photometric Catalogue, the

Palomar Transient Factory The Palomar Transient Factory (PTF, obs. code: I41), was an astronomical survey using a wide-field survey camera designed to search for optical transient and variable sources such as variable stars, supernovae, asteroids and comets. The projec ...

survey, and individual observers led by Czech astronomers Josef Hanuš and Josef Ďurech, as well as sparse-in-time photometry from the

NOFS The United States Naval Observatory Flagstaff Station (NOFS), is an astronomical observatory near Flagstaff, Arizona, US. It is the national dark-sky observing facility under the United States Naval Observatory (USNO). NOFS and USNO combine a ...

, the Catalina Sky Survey, and the La Palma surveys .

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, 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, ...

(WISE), the Infrared Astronomical Satellite

IRAS The Infrared Astronomical Satellite (Dutch: ''Infrarood Astronomische Satelliet'') (IRAS) was the first space telescope to perform a survey of the entire night sky at infrared wavelengths. Launched on 25 January 1983, its mission lasted ten mo ...

, and the Japanese Akari satellite, ''Asplinda'' measures , and kilometers in diameter, and its surface has an

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 ...

of , and , respectively. Another published measurement by the WISE team also gives a mean-diameters of with corresponding albedo of . The ''Collaborative Asteroid Lightcurve Link'' adopts the results from IRAS, that is, an albedo of 0.0415 and a diameter of 47.08 km based on 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 10.71. An asteroid occultation on 15 August 2006, gave a best-fit ellipse dimension of 47.0 × 47.0 kilometers. These timed observations are taken when the asteroid passes in front of a distant star. However the quality of the measurement is poorly rated.

Notes

References

External links

Lightcurve Database Query
(LCDB), at ''www.minorplanet.info''
Dictionary of Minor Planet Names
Google books

– Minor Planet Center * * {{DEFAULTSORT:Asplinda 000958 Discoveries by Karl Wilhelm Reinmuth Named minor planets 000958 19210928