468 Lina
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Lina (
minor planet designation A formal minor-planet designation is, in its final form, a number–name combination given to a minor planet (asteroid, centaur, trans-Neptunian object and dwarf planet but not comet). Such designation always features a leading number (catalog or ...
: 468 Lina), provisional designation ', is a dark
Themistian asteroid The Themis family (''adj. Themistian''; ) is a family of carbonaceous asteroids located in the outer portion of the asteroid belt, at a mean distance of 3.13 AU from the Sun. It is one of the largest families with over 4700 known members, and co ...
from the outer 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, called ...
, approximately in diameter. It was discovered on 18 January 1901, by German astronomer Max Wolf 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 student ...
in southwest Germany. The carbonaceous asteroid was named for the housemaid of the discoverer's family.


Classification and orbit

''Lina'' is a core member of the
Themis family The Themis family (''adj. Themistian''; ) is a Asteroid family, family of carbonaceous asteroids located in the Kirkwood gap, outer portion of the asteroid belt, at a mean distance of 3.13 Astronomical Unit, AU from the Sun. It is one of the Asteroi ...
, an ancient population of
carbonaceous Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes up ...
outer-belt asteroids with nearly coplanar ecliptical orbits. It orbits the Sun at a distance of 2.5–3.8  AU once every 5 years and 6 months (2,025 days). 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 0.20 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 0.4 ° with respect to the ecliptic. ''Lina'' was first observed at Heidelberg a few days prior to its official discovery observation. 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 with its identification as ' at Heidelberg in 1915, or 14 years 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 for "Lina", a domestic housemaid of the discoverer's family at Heidelberg. The members of Max Wolfs household figure prominently in the names of his discoveries, but background information on the name's origin behind most of them have been lost. Wolf also named 482 Petrina and 483 Seppina after the household's two dogs, a practice that was later discouraged by the
IAU The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...
. Naming citation for ''Lina'' was first 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 Cincinn ...
in 1955 ().


Physical characteristics

It has been characterized as a CPF-type and
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-t ...
by
Tholen Tholen () is a 25,000 people municipality in the southwest of the Netherlands. The municipality of Tholen takes its name from the town of Tholen, which is the largest population center in the municipality. The municipality consists of two peninsu ...
and
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 ...
, respectively.


Photometry

In December 2006, 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 ''Lina'' was obtained by American astronomer Robert Buchheim at Altimira Observatory () in California. Light-curve 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 16.33 hours with a brightness variation of 0.15
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 ...
( U=3). Its odd light curve shows multiple peaks, contrary to the classically shaped double-peaks seen in ''bimodal light curves'', that have two maximums and two minimums per rotation. ''Lina''s unusual triple-peak shape made it difficult to fit a period. Other photometric observations were taken by Edward Tedesco in the 1970s (8.3 hours; Δ mag; U=1), by
Pierre Antonini Pierre Antonini is a retired French mathematics professor and amateur astronomer who has discovered several minor planets and two supernovae at his private Observatoire de Bédoin (Bedoin Observatory; observatory code: 132) located at Bédoin, s ...
and
Raoul Behrend 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 num ...
in January 2006 (16.478 hours; Δ0.18 mag; U=2), and by Scott Marks and Michael Fauerbach in February 2007 (16.54 hours; Δ0.13 mag; U=2).


Diameter and albedo

According to the space-based surveys carried out by 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 ...
, the Japanese
Akari Akari (ASTRO-F) was an infrared astronomy satellite developed by Japan Aerospace Exploration Agency, in cooperation with institutes of Europe and Korea. It was launched on 21 February 2006, at 21:28 UTC (06:28, 22 February JST) by M-V rocke ...
satellite, the Spitzer Space Telescope, 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 2011, ...
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, ''Lina'' measures between 58.60 and 69.34 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 refl ...
between 0.043 and 0.06. The ''Collaborative Asteroid Lightcurve Link'' still adopts the results obtained by IRAS, that is an albedo of 0.043 and a diameter of 69.34 kilometers at 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 9.83, while more recent results by NEOWISE and Spitzer tend toward a higher albedo of 0.06 and a shorter diameter of 58.60 and 59.7 kilometer, respectively. Spitzer's spectra of ''Lina'' shows an emissivity plateau in the wavelength range of 9 to 12 μm, which is indicative of silicates.


References


External links


Asteroid Lightcurve Database (LCDB)
query form

)
Rock Legends: The Asteroids and Their Discoverers
Google books
Dictionary of Minor Planet Names
Google books

– Observatoire de Genève, Raoul Behrend

– Minor Planet Center * * {{DEFAULTSORT:Lina 000468 Discoveries by Max Wolf Named minor planets 000468 19010118