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

A number, → real or → complex, that is a → root of a → non-zero polynomial equation whose → coefficients are all → rational. For example, the root x of the polynomial x² - 2x + 1 = 0 is an algebraic number, because the polynomial is non-zero and the coefficients are rational numbers. The imaginary number i is algebraic, because it is the solution to x² + 1 = 0.

→ algebraic; → number.

A star which lies at the lower left-hand corner of → Pegasus. Its apparent magnitude varies between +2.80 and +2.86 over a period of 3.6 hours; → spectral type B2 IV.

Algenib, from Ar. Aljanb al-Faras "the horse's flank," from al "the" + janb "flank" + faras "horse".

A binary system in Leo the brighter component of which (magnitude 2.6) is a giant K star and the partner a giant G (magnitude 3.8). The angular separation of just over 4'' means that the two stars are at least 170 AU apart, for a distance of 126 → light-years, and have an orbital period of over 500 years.

Algieba, from Ar. Al-Jabhah "the forehead" (of the Lion).

A variable star in the constellation → Perseus, which was the first eclipsing binary discovered. Its brightness varies between 2.2 and 3.5 magnitudes. Lying at a distance of about 82 → light-years, it consists of at least three components. The brightest component (A) is of spectral type B8 V, and the second one (B) a K type giant. The components A and B turn around each other with a period of about 68.8 hours.

Algol, from Ar. Ra's al-ghul "the ghoul's head".

The same as eclipsing binary stars, the prototype of which is Algol.

→ Algol; → variable.

1) A step-by-step problem-solving procedure, especially an established, recursive computational procedure for solving a problem in a finite number of steps.
2) Historically, the Arabic system of arithmetical notation (with the figures 1, 2, 3, etc.); the art of computation with the Arabic figures, one to nine, plus the zero; arithmetic.

From M.L. algorismus, a mangled transliteration of al-Khwarizmi, "native of Khwarazm," the surname of the Persian mathematician and astronomer Abu Ja'far Mohammad ibn Musa al-Khwarizmi (c780-c850).

Xârazmik, from Xârazmi (or Xwârazmi, from Xwârazm), the name of the Persian mathematician, + Persian affix → -ik, → -ics.

General:An assumed name; otherwise called.
Electronics: A false signal in telecommunication links from beats between signal frequency and sampling frequency.

From L. alius "(an)other". Compare with Skt. anya "other, different," Av. anya-, O.Pers. aniya- "the one or the other," Arm. ail, Gk. allos "another," Goth. aljis "other". PIE *al- "beyond".

Anyâ from Mid.Pers. anya "other, otherwise," from Av. anya "other". This term is used as eyni in the Modern Persian Aftari dialect: eyni sâl "other year," eyni vacé "other child".

The condition that two or more functions are indistinguishable because they have the same values at a finite set of points. Such functions are said to be aliases of each others. The aliasing problem often occurs in undersampled discrete Fourier transform.

Aliasing, from → alias + → -ing.

Anyâyi, from anyâ, → alias, + noun forming suffix -i.

A claim or piece of evidence that one was elsewhere when an act, typically a criminal one, is alleged to have taken place (OxfordDictionaries.com).

From L. alibi (adv.) "elsewhere, somewhere else," locative of alius "another, other, different," → alias.

Enigâh, literally "other place," from eni, from Mid.Pers. anya "other," → alias, +gâh "place," → time.

1) In a → planispheric astrolabe, the small revolving rod fixed to the center of the goniometric scale plotted on the → front or → back of the instrument. Unlike the → rule, the alidade has little vanes with holes or slots at each end, called → pinnules, which are used as sights, through which the observer can aim at a particular object. An index, often consisting of the edge of the alidade itself, shows on the goniometric scales the angle between the line of sight of the targeted object and a predetermined axis, i.e. the vertical of the observation locality (online museo galileo, VirtualMuseum).
2) A rule having a sight at each end, used in surveying.
3) A topographic surveying and mapping instrument used for determining directions, consisting of a telescope and attached parts.

M.E. allidatha, alhidade, from L. alhidada, from Ar. al-'izâda (العضاده), from al- "the" + 'izâda "an armlet, a bracelet; a sickle-like piece of metal, used by camel drivers, to pull down tree branches to camels."

Ezâdé, from Ar. al-'izâda.

1) A species not native to its environment; an introduced species.
2) A hypothetical creature from outer space; → extraterrestrial.

M.E., from O.Fr. alien "strange, foreign; a stranger, foreigner," from L. alienus "of or belonging to another, foreign, alien, strange," also, as a noun, "a stranger, foreigner," adjectival form of alius "(an)other," → alias; meaning "not of the Earth" first recorded 1920.

Bigâné "alien, foreigner," from Mid.Pers. bêgânag, from bêg-, bê- "out, outside, apart" (cf. Sogd. bêk "out, outside, apart, except," bêk-dênê "heretic," literally "out of religion") + suffix -ânag.

To arrange in a line or so as to be parallel; to adjust to produce a proper relationship or orientation.

M.Fr. aligner, from O.Fr. aligner, from à "to" + ligner "to line," from L. lineare, from linea "linen thread, string, line;" → line.

Âxatidan, from â- intesive and nuance prefix + xat, → line, + infinitive suffix -idan.

Setting the axis of a telescope parallel to prime directions. In equatorial mounting, they are made parallel with the Earth's axis of rotation and the equator respectively. → collimation.

→ align; → telescope.

Arranged in a → straight line.

Past participle of → align.

A magnetic field whose lines of force are oriented along a particular direction or by a particular manner (axially, vertically; randomly, properly, etc.)

→ aligned; → magnetic field.

The fact of being in line or bringing into line.

Verbal noun of → align; → -ment.

The brightest of the seven stars that make up the → Big Dipper → asterism. Alioth shines at magnitude +1.77 from a distance of about 80 → light-years. It is a white star of → spectral type A0pCr. The spectrum of the star is characterized by abnormally strong lines of → chromium and → europium.

Alioth, from Aliot, from Ar. Alyat (الیه) "tail, buttocks".

Jown, from Ar. Jawn "black camel or horse".

The second brightest star in → Ursa Major and the end star in the handle of the → Big Dipper. Alkaid is a blue B3V main sequence star of apparent magnitude of 1.86 and lies at about 100 → light-years.

Alkaid "leader, chief," from Al-Qa'id al-Banat an-Na'ash "the leader of the daughters of the bier," from Banat "daughters" + Na'ash "bier". Banat an-Na'ash is the Ar. name of the constellation.

Qâed from Ar. Al-Qa'id.

A substance that dissolves in water to give hydroxide ions. A generic name for → bases.

M.E. alkaly, from M.fr. alcali, M.L. alkali, from Ar. al-qily (القلی) "salt wort," a plant growing in alkaline soils.

Qalyâ, loan from Ar., as above.

A spectral line produced by an → alkali metal.

→ alkali; → line.