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 cons ...
from the outer regions 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 ...
. It was discovered on 23 September 1917, by Soviet astronomer
Sergey Belyavsky
Sergey Ivanovich Belyavsky (russian: Серге́й Ива́нович Беля́вский; December 7, 1883 (Julian calendar: November 25) – October 13, 1953) was a Soviet/Russian astronomer and a discoverer of 36 numbered minor planets ...
at the
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 f ...
on the Crimean peninsula. The presumed
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 short
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 4.9 hours and measures approximately in diameter. It was likely named after Ulrike von Levetzow, last love of
Goethe
Johann Wolfgang von Goethe (28 August 1749 – 22 March 1832) was a German poet, playwright, novelist, scientist, statesman, theatre director, and critic. His works include plays, poetry, literature, and aesthetic criticism, as well as treat ...
.
Orbit and classification
When applying the synthetic
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 ...
Milani Milani (or Milāni) is an Italian surname. Notable people with the surname include:
*Abbas Milani (born 1949), Iranian-American historian and author
*Alfredo Milani (born 1924), Italian motorcycle racer
*Andrea Milani, several people
** Andrea Mila ...
and Knežević (AstDys), ''Ulrike'' 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 ...
(), a large
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 a ...
of carbonaceous asteroids named after
24 Themis
Themis ( minor planet designation: 24 Themis) is one of the largest asteroids in the asteroid belt. It is also the largest member of the Themistian family. It was discovered by Annibale de Gasparis on 5 April 1853. It is named after Themis, th ...
. However, according to another HCM-analysis by Nesvorný, it is a
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 a ...
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 numb ...