rectilinear propagation of light
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
Fr.: système rectilinéaire
Fr.: se reproduire périodiquement, revenir
To occur again, as an event, experience, etc.
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."
1) An act or instance of recurring.
Verbal noun of → recur.
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.
Occurring or appearing again, especially repeatedly or periodically (Dictionary.com). → recurrence nova.
Verbal adj. from → recur.
Fr.: nova récurrente
Fr.: récursion, récursivité
1) A running backward, return.
From L. recursionem (nominative recursio); → recurrent.
Bâzâneš, verbal noun of bâzâmadan, → recur.
1) Pertaining to or using a rule or procedure that can be applied repeatedly.
Adjective from → recursion.
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)!
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.
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).
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."
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 star
setâre-ye gude-ye sorx
Fr.: étoile du grumeau rouge
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.
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 branch (RGB)
šâxe-ye qulân-e sorx
Fr.: branche des géantes rouges
red HB star
Fr.: étoile RHB
Same as → red horizontal branch star.
red horizontal branch star
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.