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

In a compact, steady radio-source where the density of relativistic electrons and the density of synchrotron radiation due to these electrons are very large, the radio photons should be transformed into X-ray and gamma-ray photons through inelastic Compton scatterings onto the relativistic electrons. Thus the radio photons should rapidly disappear and only gamma-ray photons should be observed. This phenomenon does not take place if the radio source is in relativistic expansion.

→ Compton; → catastrophe.

Increase in the wavelength (reduction in the energy) of an → X-ray or → gamma ray  → photon when it collides a → free → electron.

→ Compton; → effect.

Theoretical equation which gives the change in the photon wavelength due to the → Compton effect.

→ Compton; → equation.

The change of direction undergone by the electron in the → Compton effect. The scattered photon and the collided electron move in different directions from that of the incident photon.

→ Compton; → recoil.

Scattering of a → photon due to the → Compton effect.

→ Compton; → scattering.

Of the → Compton effect, the amount of increase in the wavelength of an energetic photon upon its collision with an electron.

→ Compton; → shift.

In → gamma ray → spectroscopy, a technique to reduce the contribution of gamma rays generated by → Compton scattering.

→ Compton; → suppression.

The quantum wavelength of a particle with a highly relativistic velocity. The Compton wavelength is given by h/mc, where h is Planck's constant, m is the mass of the particle, and c the light speed. For an electron, the Compton wavelength is about 2.4 × 10^-10 cm, intermediate between the size of an atomic nucleus and an atom.

→ Compton; → wavelength.

The change in the → spectrum of → electromagnetic radiation due to → scattering from → electrons. When → photons and electrons coexist in the same volume of space, their → collisions can → transfer energy from photons to electrons (→ Compton effect) or from electrons to photons (→ inverse Compton effect).

Verbal noun of → Comptonize; → -tion.

The verb describing the → Camptonization process.

→ Compton; → -ize.

Emission undergone → Comptonization.

→ Comptonize; → emission.

The action or state of forcing or being forced to do something; constraint (OxforddDctionaries.com).

M.E., from O.Fr. compulsion, from L. compulsion-, noun of action from past-participle stem of compellere, → compel.

Verbal noun from vâdâridan, vâdâr kardan, → compel.

Required by law or a rule; obligatory; involving or exercising compulsion; coercive (OxforddDctionaries.com).

From M.L. compulsorius, from L. compulsus, p.p. of compellere, → compel.

Adjective from vâdâreš, vâdârkard, → compulsion.

The act, process, or method of calculating.

Verbal noun of → compute.

To determine by calculation, especially by numerical methods; to determine by using a computer or calculator. See also → calculate.

From Fr. computer, from L. computare "to count, sum up," from → com- "with" + putare "to prune, clean, settle an account, think over, reflect;" PIE base *pau- "to cut, strike, stamp."

Hesâbidan, from Ar. hesâb "reckoning, computation," + infinitive suffix -idan.

An electronic device which can accept data, apply a series of logical instructions rapidly, and supply the results of the processes as information.

From → compute + suffix → -er.

Râyângar "arranger, organizer," on the model of Fr. ordinateur according to which the electronic device arranges/organizes instructions and information. Râyângar, from râyân- stem of râyânidan "to regulate, set in order," from Mid.Pers. râyânīdan "to arrange, organize" + -gar agent suffix. Râyân-, from rây-, Mod.Pers. ârây-, ârâyeš, ârâyidan "to arrange, adorn," Mid.Pers. ârây-, ârâstan "to arrange, adorn;" O.Pers. rād- "to prepare," rās- "to be right, straight, true," rāsta- "straight, true" (Mod.Pers. râst "straight, true"); Av. rāz- "to direct, put in line, set," razan- "order;" Gk. oregein "to stretch out;" L. regere "to lead straight, guide, rule," p.p. rectus "right, straight;" Skt. rji- "to make straight or right, arrange, decorate;" PIE base *reg- "move in a straight line;" see also → direct.

A segment of self-replicating code planted illegally in a computer program, often to damage or shut down a system or network (Dictionary.com).

→ computer; → virus.

The process or state of computerizing.

→ computerize.

To control, perform, process, or store by means of or in an electronic computer or computers.

From → computer + verb forming suffix → -ize.

Of a surface, curving inward.

From L. concavus "hollow," from → com- intensive prefix + cavus "hollow;" PIE base *keu- "a swelling, arch, cavity."

Kâv "hollow," verb kâvidan (kâftan) "to dig; to examine, investigate," cf. L. cavus "hollow" (E. derivatives: cavity, concave, cave, excavate), Gk. koilos "hollow," Armenian sor; PIE *kowos "hollow."