An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



Number of Results: 20 Search : cross
collisional cross section
  سکنج ِ اسکرمند ِ همکوبشی   
sekanj-e oskarmand-e hamkubeši

Fr.: section efficace de collision   

Same as → cross section.

collisional; → cross; → section.

  چلیپا، خاج   
calipâ (#), xâj (#)

Fr.: croix   

(n.) 1a) The Southern Cross, → Crux. 1b) A figure or pattern formed by the intersection of two lines.
(adj.) 2a) Involving interchange; reciprocal. 2b) Lying or passing crosswise; intersecting.

M.E. cros, from O.E., probably from Old Norse kross, from O.Ir. cros, from L. crux "stake, cross."

Calipâ, loanword from Aramaic. Xâj loanword from Arm.

cross correlation
  هم‌باز‌آنش ِ چلیپایی، ~ خاجی   
hamvbâzâneš-e calipâyi, ~ xâji

Fr.: corrélation croisée   

In radio astronomy, the process performed by a → cross correlator or the result of the process.

cross; → correlation.

cross correlator
  هم‌باز‌آن‌گر ِ چلیپایی، ~ خاجی   
hambâzângar-e calipâyi, ~ xâji

Fr.: corrélateur   

In radio interferometry, a device that multiplies together the signals received by each pair of antennas in an array and performs several operations on the signal (filtering out the noise added to the signal by the receiver electronics, correcting for the Doppler shift and geometric delay due to the position and motion of the antennas). The correlated signal, corresponding to the spatial frequency given by the distance between the two antennas, is then combined with the other spatial frequency to reconstruct the map of the source.

cross; → correlator.

cross disperser
  پاشنده‌ی ِ چلیپایی، ~ خاجی   
pâšande-ye calipâyi, ~ xâji


A device producing cross dispersion.

cross; → disperser.

cross dispersion
  پاشش چلیپایی، ~ خاجی   
pâšeš-e calipâyi, ~ xâji

Fr.: dispersion croisée   

Dispersion of a light beam by using two dispersing elements (grating, grism), one for separating spectral orders, the other for resolving spectral features within an order.

cross; → dispersion.

cross identification
  ایدانش ِ چلیپایی   
idâneš-e calipâyi

Fr.: identification croisée   

The identification of an object in a data base or catalog and matching it with the same object identified in another catalog.

cross; → identification.

cross product
  فر‌آورد ِ برداری   
farâvard-e bordâri

Fr.: produit vectoriel   

Same as → vector product.

cross; → product.

cross reference
  بازبرد ِ دوسویه، ~ چندسویه   
bâzbord-e dosuyé (#), ~ candsuyé (#)

Fr.: référence croisée   

Reference from one part or element of a book or data catalog to something in another for further information.

cross; → reference.

cross section

Fr.: 1) section plane; 2) section efficace   

1) Math: The intersection of a plane with a geometric figure, usually at right angles to an axis of symmetry.
2) Physics: A quantity that expresses the effective area that a given particle presents as a target to another incident particle, giving a measure of the probability that the incident particle will induce a particular atomic or nuclear reaction. Also called collision cross section. The cross section has the dimensions of a surface. In nuclear and particle physics, the commonly used units for the cross section are the barn and cm2.

In classical mechanics, the cross section for the collision of a point particle with a hard sphere is just be the surface of a section through the middle of the sphere. This explains the name "cross section." → cross; → section.

cross-dispersing spectrograph
  بیناب‌نگار با پاششِ چلیپا‌یی، ~ ~ ~ خاجی   
binâbnegâr bâ pâšeâš-e chalipaayi, ~ ~ ~ xâji

Fr.: spectrographe à dispersion croisée   

A spectrograph that utilizes cross dispersion.

cross; → dispersion; → spectrograph.

târbast (#)

Fr.: réticule   

A system of two perpendicular fine threads of wire placed in the focus of the eyepiece of an optical instrument and used as a sighting reference.

cross; → hair.

Târbast, from târ + bast. The first component târ "thread, string, wire," cognate with tanidan, tan- "to spin, twist, weave," → tension; the second component bast "to bind; to arrange" (past stem of bastan, from Mid.Pers. bastan/vastan "to bind, shut," → band.

crossing time
  زمان ِ گذر   
zamân-e gozar (#)

Fr.: temps de traversée   

A concept used for checking the stability of a group of mass such as a cluster of galaxies or a stellar cluster. The crossing time is given by tc = R/V, where R is the average projected radial distance of group members from the center of mass and V the Gaussian dispersion in internal velocity.

cross; → time.

Zamân, → time; gozar "crossing," infinitive gozaštan, Mid.Pers. vitartan "to pass," Sogdian wytr "to go," O.Pers./Av. vitar- "to put across," from prefix vi- "away, apart," + tar- "to cross over" (Skt. tr- "to cross over," tarati "crosses," cf. Av. taro, Skt. tirah "through, beyond," L. trans "beyond," Ger. durch, E. through; PIE base *tr- "through").

Einstein cross
  چلیپای ِ اینشتین   
calipâ-ye Einstein

Fr.: croix d'Einstein   

An image of a distant quasar (redshift 1.7) formed by a foreground spiral galaxy (redshift 0.039) through gravitational lensing. The image of the quasar is split into four point sources forming a cross at the center of the galaxy.

Einstein; → cross.

intersystem crossing
  گذر ِ اندر-راژمانی   
gozar-e andar-râžmâni

Fr.: conversion intersystème   

A → radiationless relaxation process in which a molecule in some excited → electronic state converts to a state of different spin → multiplicity. Intersystem crossing is analogous to → internal conversion.

intersystem; → crossing.

Mills cross
  چلیپای ِ میلز   
calipâ-ye Mills

Fr.: croix de Mills   

A design of → radio interferometer made of two lines of → antennae at right angles to one another.

Named after the Australian engineer and astronomer Bernard Yarnton Mills (1920-2011; see R.H. Frater et al. 2013, arXiv:1306.6371); → cross.

Northern Cross
  چلیپای ِ هودری   
calipâ-ye hudari

Fr.: Croix du Nord   

An arrangement of stars in the form of a cross in the constellation → Cygnus.

north; → cross.

nuclear cross-section
  سکنج‌گاه ِ هسته‌ای   
sekanjgâh-e hasteyi

Fr.: section efficace nucléaire   

Apparent cross-section possessed by an atomic nucleus when it undergoes a particular type of collision process.

nuclear; → cross section.

Southern Cross
  چلیپای ِ دشتری   
calipâ-ye daštari

Fr.: Croix du Sud   

Popular name for the constellation → Crux. Its four brightest stars form a distinctive cross shape.

southern; → Crux.

Thomson cross section
  سکنج‌گاه ِ تامسون   
sekanjgâh-e Thomson

Fr.: section efficace de Thomson   

The → cross section involved the → Thomson scattering of electromagnetic waves by a free electron. It is defined by: σT = 8πre2/3, where re is the classical → electron radius. Its value is 0.665 245 x 10-28 m2.

Thomson; → cross; → section.