An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < R a rad rad rad rad rad rad Ram Rap ray rea rea rec rec red red ref ref reg rel rel rel rep res res res res ret RHB rid rig ris roc Ros rot rub Rut > >>

Number of Results: 726
rectilinear propagation of light
  توچش ِ راست‌خط ِ نور   
tuceš-e râst-xatt-e nur

Fr.: propagation rectiligne de la lumière   

The motion of light in the first approximation, as evidenced from the formation of shadows and other every day experience. However, → diffraction

rectilinear; → propagation; → light.

rectilinear system
  راژمان ِ راست‌خط   
râžmân-e râst-xatt

Fr.: système rectilinéaire   

An optical system that is corrected for → distortion and → spherical aberration and therefore forms the image of a straight line as a straight line.

rectilinear; → system.


Fr.: se reproduire périodiquement, revenir   

To occur again, as an event, experience, etc.

From L. recurrere "to return, run back," → re- + currere "to run," → current.

Bâzâmadan "to come back, return," from bâz, → re-, + âmadan "to come, arrive, become" (present stem ây-); Av. ay- "to go, to come," aēiti "goes;" O.Pers. aitiy "goes;" Skt. e- "to come near," eti "arrival;" L. ire "to go;" Goth. iddja "went;" Lith. eiti "to go;" Rus. idti "to go."


Fr.: récurrence   

1) An act or instance of recurring.
2) Return to a previous condition, habit, subject, etc. ( → recurrence relation.

Verbal noun of → recur.

recurrence relation
  باز‌آنش ِ باز‌آمد   
bâzâneš-e bâzâmad

Fr.: relation de recurrence   

A → sequence based on a → rule that gives the next → term as a → function of the previous term(s). For example, the sequence 3, 9, 21, 45,... can be represented by the recurrence relation un+1 = 2un + 3, where u1 = 3 and n ≥ 1.

recurrence; → relation.


Fr.: récurrent   

Occurring or appearing again, especially repeatedly or periodically ( → recurrence nova.

Verbal adj. from → recur.

recurrent nova
  نو‌اختر ِ باز‌آیند   
now-axtar-e bâzâyand

Fr.: nova récurrente   

A → cataclysmic variable star that undergoes → outbursts similar to those found in novae.

recurrent; → nova.


Fr.: récursion, récursivité   

1) A running backward, return.
2) Math.: A process in which objects are defined by the repeated application of a rule or algorithm.

From L. recursionem (nominative recursio); → recurrent.

Bâzâneš, verbal noun of bâzâmadan, → recur.


Fr.: récursif   

1) Pertaining to or using a rule or procedure that can be applied repeatedly.
2) Math.: Pertaining to or using the process of → recursion.

Adjective from → recursion.

recursive definition
  هدارش ِ باز‌آیشی   
hedâreš-e bâzâyeši

Fr.: définition récursive   

Math.: A definition of a function from which values of the same function can be calculated in a finite number of steps. In mathematical logic and computer science, a recursive definition is used to define an object in terms of itself. An example is the → factorial: n! = n*(n-1)!

recursive; → definition.

  ۱) بازچرخ کردن؛ ۲) بازچرخ شدن   
1) bâzcarx kardan; 2) bâzcarx šodan

Fr.: 1) recycler; 2) se recycler   

1) To treat or process used material so that it can be used again.
2) To repeat or pass through a process again. → recycled pulsar.

re-; → cycle.

recycled pulsar
  پولسار ِ بازچرخ‌شده   
pulsâr-e bâzcarx šodé

Fr.: pulsar recyclé   

A → pulsar of abnormally low magnetic field and short period. The short period suggests that the pulasr is young, while the low field suggests a very old pulsar. According to theoretical models, a pulsar at some point in its evolution stops functioning as a pulsar. If it resides in a binary system (→ binary pulsar), its magnetic field decays in the interval when the companion evolves and fills its → Roche lobe. The dead pulsar is eventually spun up to life when → mass transfer from the companion begins. The pulsar gains → angular momentum from the infalling gas and increases its spin rate as more gas falls onto it. → Millisecond pulsars that spin hundreds of times per second are thought to be the result of such a transfer (see, e.g., G. Srinivasan, 2010, New Astronomy Reviews 54, 93, and references therein).

recycle; → pulsar.

sorx (#)

Fr.: rouge   

That part of the electromagnetic spectrum, with a wavelength between 610 and 780 nm, that produces the impression of a variety of colors resembling that of blood.

M.E. red, from O.E. read (cf. Dan. rød, M.Du. root, Ger. rot), from PIE base *reudh- (cf. Av. raoidita- "red, reddish;" Skt. rudhirá- "red, bloody;" L. ruber "red;" Gk. erythros "red").

Sorx "red" (variants Tâleši sər, Kurd. sûr), from Mid.Pers. suxr "red;" O.Pers. θuxra-; Av. suxra- "red, of fire-color;" Ossetic syrx, surx "red;" cf. Skt. śukrá- "clear, pure, bright."

red clump
  گوده‌ی ِ سرخ   
gude-ye sorx

Fr.: grumeau rouge   

A concentration, on the → horizontal branch, of → red giant stars that roughly have the same intrinsic brightness. These core → helium burning stars are the metal rich equivalents of the better known → horizontal branch stars. Theoretical models predict that their absolute luminosity only weakly depends on their age and chemical composition.

red; → clump.

red clump star
  ستاره‌ی ِ گوده‌ی ِ سرخ   
setâre-ye gude-ye sorx

Fr.: étoile du grumeau rouge   

A star on the → horizontal branch which results from the evolution of a → red giant with an initial mass of ~ 1 Msun.

red; → clump; → star.

red dwarf
  کوتوله‌ی ِ سرخ   
kutule-ye sorx (#)

Fr.: naine rouge   

A small, cool, very faint, main sequence star whose surface temperature is under about 3500 K. Red dwarfs generally have masses of less than one-third that of the Sun. In the neighbourhood of the Sun the majority of stars are red dwarfs.

red; → dwarf.

red giant
  غول ِ سرخ، غولپیکر ِ ~   
qul-e sorx (#), qulpeykar-e ~ (#)

Fr.: géante rouge   

A certain star of spectral type K or later that occupies the upper right portion of the → H-R diagram. Red giants are evolved stars that have exhausted their hydrogen fuel in the core. They may have a → luminosity up to 1000 times greater than → main sequence stars of the same → spectral type. Red giants belong to the → luminosity class III or II (bright giants). They are luminous because of their great size, but have a relatively low surface temperature. All normal stars are expected to pass eventually through a red-giant phase as a consequence of stellar evolution. When a main sequence star has converted approximately 10% of its hydrogen to helium, nuclear reactions in the core stop (→ Schönberg-Chandrasekhar limit). The → hydrostatic equilibrium is no longer maintained, and the core contracts while the outer layers expand and cool. This process produces the low surface temperature and large size (from 10 to 100 times that of the Sun) that characterize the red giant. In the core the temperature continues to rise. When it approaches 100,000,000 K helium will begin to fuse into carbon. → helium flash. Prominent bright red giants in the night sky include → Aldebaran and → Arcturus.

red; → giant.

red giant branch (RGB)
  شاخه‌ی ِ غولان ِ سرخ   
šâxe-ye qulân-e sorx

Fr.: branche des géantes rouges   

The evolutionary path of a star that has exhausted its available hydrogen content in the core, between the → main-sequence turnoff and the → helium flash.

red giant; → branch.

red HB star
  ستاره‌ی ِ BHR   
setâre-ye RHB

Fr.: étoile RHB   

Same as → red horizontal branch star.

red; → horizontal; → branch; → star.

red horizontal branch star
  ستاره‌ی ِ سرخ ِ شاخه‌ی ِ افقی   
setâre-ye sorx-e šâxe-ye ofoqi

Fr.: étoile rouge de la branche horizontale   

A star found on the red part of the → horizontal branch. According to theoretical models, these stars result from the evolution of stars with a mass around 0.8 Msun, higher than that giving rise to → BHB stars. Upon helium burning in their cores, the remnant envelope of the red giant collapses.

red; → horizontal; → branch; → star.

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