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

Hilda asteroid The Hilda asteroids (adj. ''Hildian'') are a List of minor-planet groups#Other groups out to the orbit of Jupiter, dynamical group of more than 6,000 asteroids located beyond the asteroid belt but within Jupiter's orbit, in a 3:2 orbital resonanc ...

, approximately in diameter, located in the outermost region 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 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 He ...

at the

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 southwest Germany. The assumed

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 ...

has a

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 16.5 hours and is likely elongated in shape. It was named after Swedish astronomer Bror Asplind (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 6,000 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 In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relation ...

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 Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...

. It is however not a member of the collisional

Hilda family The Hilda family ( 001) is an ancient collisional asteroid family of at least 409 known asteroids, named for its largest member, the -across asteroid 153 Hilda. It lies within the larger dynamical group of Hilda asteroids, a group of asteroids ...

() but a non-

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

asteroid of the background population when applying the

hierarchical clustering method 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 ...

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 quantities ...

. 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 longe ...

of 3.98 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 0.18 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 reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

of 6 ° 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 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 ci ...

(1890–1954), a Swedish astronomer and orbit computer. The following, sequentially numbered asteroids 959 Arne, 960 Birgit and 961 Gunnie are named after his three children, respectively. The 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 Cincinna ...

'' by

Paul Herget 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 Cincinna ...

in 1955 ().

Physical characteristics

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 ...

has been published for ''Asplinda''. As an Hildian asteroid with a low albedo ''(see below)'' it is a carbonaceous

(assumed), or possibly a D-type or

P-type asteroid P-type (primitive-type) asteroids 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 (celestial body), trojan Libration point orbit, librat ...

population.

Rotation period and poles

In December 2017, 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 ''Asplinda'' was obtained from photometric observations by Brian Warner,

Robert Stephens Sir Robert Graham Stephens (14 July 193112 November 1995) was an English actor in the early years of Britain's Royal National Theatre. Early life Stephens was born in Shirehampton, Bristol, in 1931, the eldest of three children of shipyard ...

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 The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomi ...

in California. Lightcurve analysis gave a

of hours with a high brightness amplitude of

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 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 In astronomy, the ecliptic coordinate system is a celestial coordinate system commonly used for representing the apparent positions, orbits, and pole orientations of Solar System objects. Because most planets (except Mercury) and many small So ...

(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 Josef may refer to *Josef (given name) *Josef (surname) * ''Josef'' (film), a 2011 Croatian war film *Musik Josef Musik Josef is a Japanese manufacturer of musical instruments. It was founded by Yukio Nakamura and is the only company in Japan spec ...

, as well as sparse-in-time photometry from the NOFS, the

Catalina Sky Survey Catalina Sky Survey (CSS; obs. code: 703) is an astronomical survey to discover comets and asteroids. It is conducted at the Steward Observatory's Catalina Station, located near Tucson, Arizona, in the United States. CSS focuses on the searc ...

, and the La Palma surveys .

Diameter and albedo

According to the surveys carried out by 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 ...

(WISE), the Infrared Astronomical Satellite

IRAS The Infrared Astronomical Satellite (Dutch language, Dutch: ''Infrarood Astronomische Satelliet'') (IRAS) was the first space telescope to perform a astronomical survey, survey of the entire night sky at infrared wavelengths. Launched on 25 Janu ...

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

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 ...

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 of 10.71. An

asteroid occultation An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks f ...

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