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

A → window function that is constant inside a specified interval.

→ rectangular; → window.

1) Math.: The process of determining the length of a curve.
2) Physics: Conversion of an alternating into a direct current.
3) Astro.: The process of rectifying a spectrum.

Verbal noun of → rectify.

A spectrum after correction for detector's → baseline.

Rectified p.p. of → rectify; → spectrum.

1) General: A person or thing that rectifies.
2) Physics: A device for transforming an → alternating current into a → direct current.

Agent noun of → rectify.

1) General: To make, put, or set right; to correct.
2) Electricity: To convert an → alternating current into a → direct current.
3) Chem.: To refine a substance, especially by repeated distillation or sublimation.

M.E. rectifien, from O.Fr. rectifier "to make straight," from L.L. rectificare "make right," from L. rectus "straight," cognate with Pers. râst, as below, → right + root of facere "to make, do, perform" (cf. Fr. faire, Sp. hacer), from PIE base *dhe- "to put, to do" (cf. Mod.Pers. dâdan "to give;" O.Pers./Av. dā- "to give, grant, yield," dadāiti "he gives; puts;" Skt. dadáti "puts, places;" Hitt. dai- "to place;" Gk. tithenai "to put, set, place;" Lith. deti "to put;" Czech diti, Pol. dziac', Rus. det' "to hide," delat' "to do;" O.H.G. tuon, Ger. tun, O.E. don "to do").

Râstidan, literally "to make straight, right," infinitive from râst cognate with L. rectus "straight," → right.

In a straight line; consisting of straight lines. → curvilinear

From recti- combining form of rectus, → right, + → line + -ar, variant of the adjective-forming suffix → -al.

Râst-xatt, from râst, → right, + xatt→ line.

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.

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.

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."

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

Verbal noun of → recur.

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 u_n+1 = 2u_n + 3, where u₁ = 3 and n ≥ 1.

→ recurrence; → relation.

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

Verbal adj. from → recur.

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

→ recurrent; → nova.

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.

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.

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.

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.

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.

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."

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.