An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 465
Hesperus
  ستاره‌ی ِ شامگاه   
setâre-ye šâmgâh (#)

Fr.: étoile du soir   

An → evening star, especially the planet Venus in its appearance as the evening star.

M.E., from L., from Gk. hesperos "evening, western;" → west.

Setâre-ye šâmgâh "evening star," from setâréstar + šâmgâh "evening," from šâm "evening, evening meal" + gâh "time." The first component, šâm, from Mid.Pers. šâm "evening meal, supper," from Av. xšāfnya- "evening meal," from Av. xšap-, xšapā-, xšapan-, xšafn- "night" (O.Pers. xšap- "night," Mid.Pers. šap, Mod.Pers. šab "night"); cf. Skt. ksap- "nigh, darkness;" Hittite ispant- "night." The second component gâh "time," Mid.Pers. gâh, gâs "time," O.Pers. gāθu-, Av. gātav-, gātu- "place, throne, spot;" cf. Skt. gâtu- "going, motion; free space for moving; place of abode;" PIE *gwem- "to go, come."

HESS collaboration
  همکاری ِ HESS   
hamkâri-ye HESS

Fr.: collaboration HESS   

High Energy Stereoscopic System (H.E.S.S.).

H.E.S.S.; → collaboration.

Hess diagram
  نمودار ِ هس   
nemudâr-e Hess

Fr.: diagramme de Hess   

A diagram showing the relative density of occurrence of stars at various → color-magnitude positions of the → Hertzsprung-Russell diagram for a given → galaxy.

Named after R. Hess who originated it in 1924: "Die Verteilungsfunktion der absoluten Helligkeiten in ihrer Abhängigkeit vom Spektrum". Probleme der Astronomie. Festschrift fur Hugo v. Seeliger. Springer, Berlin. p. 265; → diagram.

hetero-
  دگر-   
degar- (#)

Fr.: hétéro-   

Prefix denoting "other, different."

From Gk. heteros "the other (of two), another, different."

Degar "another, other;" from Mid.Pers. dit, ditikar "the other, the second;" O.Pers. duvitiya- "second," Av. daibitya-, bitya- "second;" Skt. dvitiya- "second," PIE *duitiio- "second."

heterodyne
  هترودین   
heterodin (#)

Fr.: hétérodyne   

1) Denoting a device or method of combining two → electromagnetic waves of different → frequency (a locally generated wave and an incoming wave) in a → nonlinear device to produce two frequencies which are equal to the → sum and → difference of the first two. The phenomenon is the counterpart of → beats produced by → sound waves. For example, heterodyning a 100-kHz and a 10-kHz signal will produce a 110-KHz and a 90-kHz signal. See also → homodyne.
2) The term heterodyne is often loosely used instead of → superheterodyne in the radio frequency field.

Heterodyne, from → hetero- + -dyne, from Gk. dynamicsdynamics; → receiver.

heterodyne interferometer
  اندرزنش‌سنج ِ هترودینی   
andarzaneš-sanj-e heterodini

Fr.: interféromètre hétérodyne   

An → interferometer using a technique that involves introducing a small → frequency shift between the optical frequencies of the two interfering light beams. This results in an intensity modulation at the → beat frequency of the two beams for any given point of the → interference pattern. A convenient way of introducing such a frequency shift is by means of an acousto-optic modulator.

heterodyne; → interferometer.

heterodyne receiver
  گیرنده‌ی ِ هترودینی   
girande-ye heterodini (#)

Fr.: récepteur hétérodyne   

superheterodyne receiver.

heterodyne; → receiver.

heterodyne technique
  تشنیک ِ هترودین   
tašnik-e heterodin

Fr.: technique hétérodyne   

superheterodyne technique.

heterodyne; → technique.

heterogeneity
  دگرگنی   
degargeni

Fr.: hétérogénéité   

The quality or state of being → heterogeneous. See also → homogeneity, → inhomogeneity.

Noun from → heterogeneous.

heterogeneous
  دگرگن   
degargen

Fr.: hétérogène   

1) Composed of parts of different kinds; having widely dissimilar elements or constituents. See also → homogeneous, → inhomogeneous.
2) Chemistry: A mixture that does not have uniform composition and properties throughout; composed of different substances or the same substance in different phases.

hetero- + -genous, → homogeneous.

heuristic
  یافتیک   
yâftik

Fr.: heuristique   

Methodology, Math.: Pertaining to a method of analyzing outcome through comparison to previously recognized patterns in the absence of an → algorithm for formal proof.

From L. heuristicus (from Gk. heuretikos "inventive," related to heuriskein "to find," from heur-) + -isticus, → -ic.

Yâftik, from yâft past tense of yâftan, yâb- "to → find" + -ik, → -ic.

hexa-
  شش-   
šeš- (#)

Fr.: hexa-   

A prefix meaning → six. → hexagon.

six.

hexagon
  شش‌بر، شش‌گوش   
šešbar (#), šešguš (#)

Fr.: hexagone   

A six-sided → polygon.

hexa-; → -gon;.

HgMn star
  ستاره‌ی ِ HgMn   
setâre-ye HgMn

Fr.: étoile HgMn   

A → chemically peculiar star of late → B-types. The most distinctive features of HgMn stars are extreme atmospheric overabundance of Hg (up to 5 dex) and of Mn (up to 3 dex). The origin of abundance anomalies observed in late B-type stars with HgMn peculiarity is still poorly understood. More than two thirds of the HgMn stars are known to belong to spectroscopic binaries with a preference of orbital periods ranging from 3 to 20 days (Hurbig et al., 2012, arXiv:1208.2910).

Hg, → mercury; Mn, → manganese; → star. mercury-manganese

Hickson Compact Group (HCG)
  گروه ِ همپک ِ هیکسون   
goruh-e hampak-e Hickson

Fr.: groupe compact de Hickson   

A list of 100 compact groups of galaxies that were identified by a systematic search of the → Palomar Observatory Sky Survey red prints. Each group contains four or more galaxies, has an estimated mean surface brightness brighter than 26.0 magnitude per arcsec2 and satisfies an isolation criterion.

Hickson, Paul, 1982, ApJ 255, 382; → compact; → group.

hidden
  پنهان   
penhân (#)

Fr.: caché   

Being out of sight; concealed.

From M.E., from O.E. hydan, from W.Gmc. *khuthjanan, from PIE *keudh- (cf. Gk. keuthein "to hide, conceal"), from base *(s)keu- "to cover, conceal."

Penhân "hidden," from Mid.Pers. pad nihân, from pad "to, at, for, in" (from O.Pers. paity; Av. paiti "to, toward, in, at;" cf. Skt. práti; Gk. poti) + nihân "concealment, secrecy, hiding place" (Mod.Pers. nahân), from Proto-Iranian *ni-dāna-, from ni- "down; into," → ni- (PIE), + dā- "to put; to establish; to give" (dadâiti "he gives;" cf. Skt. dadâti "he gives;" Gk. didomi "I give;" L. do "I give;" PIE base *do- "to give").

hidden mass
  جرم ِ پنهان   
jerm-e penhân (#)

Fr.: masse cachée   

Same as → missing mass, → non-luminous matter, or → dark matter.

hidden; → mass.

hidden variable
  ورتنده‌ی ِ پنهان   
vartande-ye penhân

Fr.: variable caché   

A theory based on the hypothesis that the discrepancies with respect to classical reality found in → quantum mechanics stem from our lack of knowledge about the observed system (→ EPR paradox). According to this hypothesis, the system should be described by additional quantum parameters, of still unknown nature, but different from position, velocity, spin, etc. The hidden variable theory has been ruled out by the violation of → Bell's inequality for all theories with local property, as suggested by the → Aspect experiment.

hidden; → variable.

hierarchical
  پایگانی   
pâygâni

Fr.: hiérarchique   

Of, belonging to, or characteristic of a hierarchy. → hierarchical clustering; → hierarchical cosmology; → hierarchical multiple system; → hierarchical structure formation.

hierarchy; → -al.

hierarchical clustering
  خوشه‌بندی ِ پایگانی   
xušé bandi-ye pâygâni

Fr.: groupement hiérarchique   

A model in which a system of self-gravitating particles will gradually aggregate into larger and larger gravitationally bound groups and clusters.

hierarchical; → clustering.

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