924 Toni
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924 Toni ( ''prov. designation'': ''or'' ) is a large
background asteroid 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 ...
, approximately in diameter, from the outer 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 was discovered on 20 October 1919, by German 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-Königstuhl State Observatory Heidelberg-Königstuhl State Observatory () is a historic astronomical observatory located near the summit of the Königstuhl hill in the city of Heidelberg in Germany. It is operated by the ''Center for Astronomy (ZAH)'' at the University of He ...
. The
X-type asteroid The X-group of asteroids collects together several types with similar spectra, but probably quite different compositions. Tholen classification In the Tholen classification, the X-group consists of the following types: * E-type – with high ...
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 19.4 hours. It was named "Toni", a common German female name unrelated to the discoverer's contemporaries, that was taken from the almanac '' Lahrer Hinkender Bote''.


Orbit and classification

''Toni'' is 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 main belt's 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 outer asteroid belt at a distance of 2.5–3.4  AU once every 5.04 years (1,840 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 2.94 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 0.15 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 9 ° 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
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 ...
on 20 January 1906, where 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 two days later on 20 January 1906, more than 13 years prior 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 "Toni", after a female name picked from the '' Lahrer Hinkender Bote'', published in
Lahr Lahr (officially Lahr/Schwarzwald since 30 September 1978) (); ) is a city in western Baden-Württemberg, Germany, approximately 50 km north of Freiburg, Freiburg im Breisgau, 40 km southeast of Strasbourg, and 95 km southwest of Ka ...
, southern Germany. A ''Hinkender Bote'' (lit. "limping messenger") was a very popular
almanac An almanac (also spelled almanack and almanach) is a regularly published listing of a set of current information about one or multiple subjects. It includes information like weather forecasting, weather forecasts, farmers' sowing, planting dates ...
, especially in the alemannic-speaking region from the late 17th throughout the early 20th century. The
calendar A calendar is a system of organizing days. This is done by giving names to periods of time, typically days, weeks, months and years. A calendar date, date is the designation of a single and specific day within such a system. A calendar is ...
section contains
feast days The calendar of saints is the traditional Christian method of organizing a liturgical year by associating each day with one or more saints and referring to the day as the feast day or feast of said saint. The word "feast" in this context does n ...
, the dates of important fairs and astronomical ephemerides. The German
name day In Christianity, a name day is a tradition in many countries of Europe and the Americas, as well as Christian communities elsewhere. It consists of celebrating a day of the year that is associated with one's baptismal name, which is normatively t ...
analogue is given next to the protestant and catholic entries in the
calendar of saints The calendar of saints is the traditional Christian method of organizing a liturgical year by associating each day with one or more saints and referring to the day as the feast day or feast of said saint. The word "feast" in this context does n ...
''(entry not found)''.


Reinmuth's ''calendar names''

As with 22 other asteroids – starting with 913 Otila, and ending with 1144 Oda – Reinmuth selected names from this calendar due to his many asteroid discoveries that he had trouble thinking of proper names. These names are not related to the discoverer's contemporaries. Lutz Schmadel, the author of the ''Dictionary of Minor Planet Names'' learned about Reinmuth's source of inspiration from private communications with Dutch astronomer
Ingrid van Houten-Groeneveld Ingrid van Houten-Groeneveld (; ; 21 October 1921 – 30 March 2015) was a Dutch astronomer. Background In a jointly credited trio with Tom Gehrels and her husband Cornelis Johannes van Houten, she was the discoverer of many thousands of as ...
, who worked as a young astronomer at Heidelberg.


Physical characteristics

In the Bus–Binzel
SMASS classification An asteroid spectral type is assigned to asteroids based on their reflectance spectrum, color, and sometimes albedo. These types are thought to correspond to an asteroid's surface composition. For small bodies that are not internally different ...
, ''Toni'' is an
X-type asteroid The X-group of asteroids collects together several types with similar spectra, but probably quite different compositions. Tholen classification In the Tholen classification, the X-group consists of the following types: * E-type – with high ...
, while in the Tholen classification, it is closest to a common, 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 ...
and somewhat similar to an X-type (CX).


Rotation period

In July 2014, 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 ''Toni'' was obtained from photometric observations by Frederick Pilcher at the Organ Mesa Observatory in New Mexico. Lightcurve analysis gave a well-defined
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 hours with a 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 ...
(). This result supersedes previous observations with tentative period determinations by French amateur astronomers René Roy and
Laurent Bernasconi 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 object, near-Earth and main-belt asteroids, Jupiter trojans and Distant minor planet, distant ob ...
().


Diameter and albedo

According to the survey 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 Japanese Akari satellite, and 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 ...
, ''Toni'' measures (), () and () 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 ...
of (), () and (), respectively. The ''Collaborative Asteroid Lightcurve Link'' adopts the results obtained by IRAS, that is, an albedo of 0.0432 and a diameter of 85.49 km based on an absolute magnitude of 9.37. Further published mean-diameters and albedos by the WISE team include () and () and albedos of () and ().


Notes


References


External links


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

Geneva Observatory, Raoul Behrend
Discovery Circumstances: Numbered Minor Planets (1)-(5000)
– Minor Planet Center * * {{DEFAULTSORT:Toni 000924 Discoveries by Karl Wilhelm Reinmuth Named minor planets 000924 000924 19191020