Asteroid Belt - Families and Groups

Families and Groups

In 1918, the Japanese astronomer Kiyotsugu Hirayama noticed that the orbits of some of the asteroids had similar parameters, forming families or groups.

Approximately one-third of the asteroids in the asteroid belt are members of an asteroid family. These share similar orbital elements, such as semi-major axis, eccentricity, and orbital inclination as well as similar spectral features, all of which indicate a common origin in the breakup of a larger body. Graphical displays of these elements, for members of the asteroid belt, show concentrations indicating the presence of an asteroid family. There are about 20–30 associations that are almost certainly asteroid families. Additional groupings have been found that are less certain. Asteroid families can be confirmed when the members display common spectral features. Smaller associations of asteroids are called groups or clusters.

Some of the most prominent families in the asteroid belt (in order of increasing semi-major axes) are the Flora, Eunoma, Koronis, Eos, and Themis families. The Flora family, one of the largest with more than 800 known members, may have formed from a collision less than a billion years ago. The largest asteroid to be a true member of a family (as opposed to an interloper in the case of Ceres with the Gefion family) is 4 Vesta. The Vesta family is believed to have formed as the result of a crater-forming impact on Vesta. Likewise, the HED meteorites may also have originated from Vesta as a result of this collision.

Three prominent bands of dust have been found within the asteroid belt. These have similar orbital inclinations as the Eos, Koronis, and Themis asteroid families, and so are possibly associated with those groupings.

Read more about this topic:  Asteroid Belt

Other articles related to "families, group, families and, families and groups":

List Of Anuran Families - Families
... Archaeobatrachia - 4 families, 6 genera, 27 species Family Genera Common Names Example Species Example Photo Ascaphidae 1 Tailed frogs Tailed Frog (Ascaphus truei) Bombinatoridae 2 ...
331 Model
331 model in particle physics offers an explanation of why there must exist three families of quarks and leptons ... no explanation of why there are three families, or indeed why there is more than one family ... anomaly, per family, and to make the three families transform differently under an extended gauge group, and to arrange that the anomaly cancel, only for ...
Utica, New York - Demographics - Organized Crime in Utica
... by the Buffalo Cosa Nostra family and at least three other families, including the Scranton, Colombo, and Genovese family which had and likely still have a local presence ... the death of Boss Stefano Magaddino and other families and influences jockeyed for power and influence, and multiple gangland style homicides took place between ... More recently in the 1990s, the infamous "Falange Crew" (A group who seemed to have highly unusual multiple and somewhat ambiguous ties to the Buffalo, Scranton ...
Asteroid Belt - Families and Groups - New Families
... Some asteroid families have formed recently, in astronomical terms ... The Karin Cluster apparently formed about 5.7 million years ago from a collision with a 33 km radius progenitor asteroid ...

Famous quotes containing the words groups and/or families:

    Belonging to a group can provide the child with a variety of resources that an individual friendship often cannot—a sense of collective participation, experience with organizational roles, and group support in the enterprise of growing up. Groups also pose for the child some of the most acute problems of social life—of inclusion and exclusion, conformity and independence.
    Zick Rubin (20th century)

    Many older wealthy families have learned to instill a sense of public service in their offspring. But newly affluent middle-class parents have not acquired this skill. We are using our children as symbols of leisure-class standing without building in safeguards against an overweening sense of entitlement—a sense of entitlement that may incline some young people more toward the good life than toward the hard work that, for most of us, makes the good life possible.
    David Elkind (20th century)