Themis family
Encyclopedia
The Themis or Themistian Asteroid Family is a Hirayama family (having similar orbital elements
) of asteroids found in the outer portion of the main asteroid belt
, between the orbits of Mars and Jupiter. At a mean distance of 3.13 AU
from the Sun
, it is one of the more populous asteroid families
. It consists of a well-defined core of larger asteroids and a surrounding region of smaller ones. This core group includes (and is named after) the asteroid 24 Themis
, discovered on April 5, 1853 by Italian astronomer Annibale de Gasparis
.
Asteroids in the Themis family share the following orbital elements:
The Themis family is one of the largest and longest-recognized dynamical families of asteroids, and is made up of C-type asteroid
s with a composition believed to be similar to that of carbonaceous chondrite
s (http://www.lpi.usra.edu/meetings/lpsc2004/pdf/1646.pdf). To date, the Themis family comprises approximately 535 known asteroids. The major ones include:
Orbital elements
Orbital elements are the parameters required to uniquely identify a specific orbit. In celestial mechanics these elements are generally considered in classical two-body systems, where a Kepler orbit is used...
) of asteroids found in the outer portion of the main asteroid belt
Asteroid belt
The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets...
, between the orbits of Mars and Jupiter. At a mean distance of 3.13 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
from the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
, it is one of the more populous asteroid families
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...
. It consists of a well-defined core of larger asteroids and a surrounding region of smaller ones. This core group includes (and is named after) the asteroid 24 Themis
24 Themis
24 Themis is one of the largest main-belt asteroids. It is also the largest member of the Themistian asteroid family. It was discovered by Annibale de Gasparis on April 5, 1853...
, discovered on April 5, 1853 by Italian astronomer Annibale de Gasparis
Annibale de Gasparis
Annibale de Gasparis was an Italian astronomer. From 1864 to 1889 he was the director of the Astronomical Observatory of Capodimonte in Naples.He won the Gold Medal of the Royal Astronomical Society in 1851....
.
Asteroids in the Themis family share the following orbital elements:
- semimajor axes between 3.08 AU and 3.24 AU
- orbital eccentricities between 0.09 and 0.22
- orbital inclinations of less than 3°
The Themis family is one of the largest and longest-recognized dynamical families of asteroids, and is made up of C-type asteroid
C-type asteroid
C-type asteroids are carbonaceous asteroids. They are the most common variety, forming around 75% of known asteroids, and an even higher percentage in the outer part of the asteroid belt beyond 2.7 AU, which is dominated by this asteroid type...
s with a composition believed to be similar to that of carbonaceous chondrite
Carbonaceous chondrite
Carbonaceous chondrites or C chondrites are a class of chondritic meteorites comprising at least 7 known groups and many ungrouped meteorites. They include some of the most primitive known meteorites...
s (http://www.lpi.usra.edu/meetings/lpsc2004/pdf/1646.pdf). To date, the Themis family comprises approximately 535 known asteroids. The major ones include:
- 24 Themis24 Themis24 Themis is one of the largest main-belt asteroids. It is also the largest member of the Themistian asteroid family. It was discovered by Annibale de Gasparis on April 5, 1853...
- 62 Erato62 Erato62 Erato is a large and dark, probably carbonaceous Themistian asteroid.Erato is the first asteroid to have been credited with co-discoverers, Oskar Lesser and Wilhelm Forster, who discovered it on September 14, 1860 from the Berlin Observatory. It was their first and only asteroid discovery...
- 90 Antiope90 AntiopeThe most remarkable feature of Antiope is that it consists of two components of almost equal size , making it a truly "double" asteroid. Its binary nature was discovered on 10 August 2000 by a group of astronomers using adaptive optics at the Keck Telescope on Mauna Kea. The "secondary" is...
- 104 Klymene104 Klymene104 Klymene is a large, dark Themistian asteroid. It probably has a carbonaceous composition. It was discovered by J. C. Watson on September 13, 1868, and named after one of the many Clymenes in Greek mythology.-References:...
- 171 Ophelia171 Ophelia171 Ophelia is a large, dark Themistian asteroid. It probably has a primitive composition, similar to that of the carbonaceous chondrite meteorites....
- 468 Lina468 Lina468 Lina is a main belt asteroid. It was discovered by Max Wolf on January 18, 1901 at Heidelberg. Its provisional name was 1901 FZ. This asteroid was named Lina after the housemaid of Max Wolf's family. It is a core member of the Themis family of asteroids....
- 526 Jena526 Jena526 Jena is a Themistian asteroid. It was discovered in Heidelberg by the German astronomer Max Wolf on March 14, 1904 and named after the city of Jena....
- 846 Lipperta846 Lipperta-External links:*...
See also
- Asteroid 4279 De Gasparis4279 De Gasparis4279 De Gasparis is a main-belt asteroid discovered on November 19, 1982 by Osservatorio San Vittore at Bologna.- External links :*...
, named in the honor of Annibale de GasparisAnnibale de GasparisAnnibale de Gasparis was an Italian astronomer. From 1864 to 1889 he was the director of the Astronomical Observatory of Capodimonte in Naples.He won the Gold Medal of the Royal Astronomical Society in 1851....
.