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

A system of two or more forces that lie along the same → line of action.

→ collinear; → force.

A mathematical property where all points lying on a line initially still lie on a line after transformation.

→ collinear; → -ity.

The act or process of colliding, → collide.

Verbal noun from → collide .

Of or relating to → collision.

→ collision; → -al.

Same as → cross section.

→ collisional; → cross; → section.

The process when the energy difference between the excited and non excited states of an atom is taken away by an electron during a collision.

→ collisional; → decay.

A physical process which is caused by the free electrons that are energized either by → photoionization or → collisional ionization. Collisional excitation puts ions, atoms, and molecules into excited states from which they may decay radiatively. Collisional excitation is important in the → interstellar medium.

→ collisional; → excitation.

A physical process whereby heat is imparted to (e.g. → interstellar dust grains or → molecular hydrogen) through collisions (with hot electrons, ions, etc.).

→ collisional; → heating.

An → ionization resulting from a → collision.

→ collisional; → ionization.

A plasma in which the → mean free path of the → charged particles between two → collisions is much smaller than the size of the system containing the plasma.

→ collisional; → plasma.

Same as the → Landau damping.

→ collision; → -less; → damping.

1) An informal meeting for the exchange of views.
2) A usually academic seminar on a broad field of study, usually led by a different lecturer at each meeting.

From L. colloquium "conference, conversation," from → com- "together" + loqui "to speak".

From Lori hacâyé "conversation among two or more people," maybe from Av. ušyāi- "to speak, talk," from vak- "to speak," Skt. vacas "speech, word," cognate with L. vox "voice," vocare "to call," Gk. ops "voice," epos "song;" PIE root *wek- "to speak".

1) A visual sensation produced in the brain when the eye views various wavelengths or frequencies of light.
2) Short for → color index.
3) A property of → quarks required to distinguish the three basic quarks of which → baryons are composed. In all → hadrons, the quarks (red, green, blue) are combined in such a way as to yield a colorless overall particle.

From M.E. colour, from O.Fr. colur, from L. color "color, hue," from Old L. colos "a covering," from PIE *kel-os- "that which covers," from *kel- "to cover, conceal."

Rang, from Mid.Pers. rang "color" (abrang "splendor"), related to Mod.Pers. razidan "to color," raxš "a mixture of red and white," also the name of Rostam's horse (loan from Sogd.?), awrang "glory, beauty, throne;" Kurd. raš "black;" cf. Skt. raj- "to color, to become red;" Gk. rezein "to color;" PIE base *(s)reg- "to color, paint" (Cheung 2007).

In the → standard model of particle physics, a property possessed by → quarks and → gluons that determine rules for how these particles may interact in the context of → quantum chromodynamics. Color charge is analogous to electromagnetic charge, but it comes in three types rather than two, which results in a different type of force, the → strong interaction. There are three pairs of colors and anti-colors, named red (anti-red), green (anti-green), and blue (anti-blue). The terminology has nothing to do with visible color. It is only a word that is used to designate three independent types of the strong charge characteristic.

→ color; → charge.

The difference between the observed → color index of a star and the intrinsic color index corresponding to its → spectral type. It indicates the modification brought to a color index by the → interstellar absorption.

→ color; excess, M.E., from O.Fr., from L. excessus "departure, going beyond," p.p. excedere "to depart, go beyond," from → ex- "out" + cedere "to go, yield."

Fozuni, from afzuni "excess," afzuni kardan "to exceed bounds," → add; → color.

The difference between the → apparent magnitude of a star measured at one standard wavelength and the apparent magnitude at another longer, standard wavelength, allowing the quantitative measure of a star's color.

→ color; → index.

The temperature of that black-body which has the same spectral energy distribution in a limited spectral region, as the object under study has.

→ color; → temperature.

Empirical mathematical transformation applied to the observed magnitudes in order to convert them into a standard system, or into a different system.

→ color; → transformation.

A diagram based on two photometric colors usually representing the same class of astronomical objects.

→ color; → diagram.

Fr.: diagramme couleur-couleur

Same as → color-color diagram.