An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A group of asteroids that share the same or similar proper orbital elements (semi-major axis, eccentricity, inclination). In 1918, the Japanese astronomer K. Hirayama first recognized some non random concentrations of asteroid elements. He noticed that certain "groups" of asteroids had similar orbital elements, and hence he first introduced the concept of "asteroid families," and identified three of them: Koronos, Eos, and Themis. The names of these groups were chosen by the parent (brightest) asteroid that the smaller group asteroids follow. Some of the more common asteroid families include the Trojans, which are actually not an asteroid family, but a group of asteroids caught in the Sun-Jupiter gravitational equilibrium points known as L3 and L4 → Lagrangian points.

→ asteroid; → family.

A group of comets with similar orbital characteristics. They result from perturbations by planets which change the diverse original orbits of the comets into those they now occupy.

→ comet; → family.

A group of entities with similar properties and common origin. → family of curves, → family of distributions, → family of sets, → comet family.

From L. familia "household, the slaves of a household," from famulus "servant," of unknown origin.

Xânevâdé "family," from xâné "house, home, houshold" + vâdé "root, foundation, origin." Xâné, from Mid.Pers. xânak, xân, xôn; cf. L. cunae "cradle;" Gk. kome "village;" Pers. Aftari dialect kiye "house, home;" PIE base *kei- "bed; to lie, to settle; beloved" (other cognates: P.Gmc. *khaim-; O.E. ham "dwelling, house, village;" E. home; Ger. Heim; L. civis "townsman;" Fr. cité; E. city; Skt. śiva- "auspicious, dear").

A set of similar curves which are distinguished by the values taken by one or more parameters in their general equation. For example, the general solution of a differential equation is represented by a family of curves.

→ family; → curve.

A set of distributions which have the same general mathematical → formula.

→ family; → distribution.

A → collection of → subsets of a set.

→ family; → set.

An → asteroid family that includes → Gaspra. The group has about 819 members and orbits between 2.17 and 2.33 → astronomical units from the Sun.

→ Flora; → family.