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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

   Homepage   
   


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer aga air Alf Alg alk Alp alt alu amm ana And ang ani ano ant ant Ap apo app app Aqu Arc arg arr asc ass ast ast asy atm ato att aur aut axi B-m bad Bal bar bar Bay Bed ber Bet bif bim bin bio bis bla ble blu Bod Bol bor bou Bra Bre bro bul C-t Cal Cam can car Car Cas cat cav cel cen cer Cha cha Cha che chl Cir cir cir Cla cli clo clu co- coc coh col col col Com com com com com com com com Com con con con con con con con con con con con con coo Cor Cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl Dan dat Dav de- Deb dec dec dee def deg del Den den der det deu dew dic dif dif dil Dip dir dis dis dis dis dis diu dod Dop dou Dra dua dus dwa dyn DZ Ear ecc eco edi EHB Ein ela ele ele ele ele ell eme emp end Eng ent epi equ equ era ESP eth Eur evi exa exc exe exi exp exp ext ext ext fac fal far fec Fer fer fie fin fir fis fla Flo flu fog for for Fou fra fre fre Fro fun G s Gal gal gal Gar gau geg gen geo geo geo ger gla gly gra gra gra gra gra Gre gro GYR Had Hal hap Har HD hea hel hel Hen Her hex hig Hil hol Hoo hor hou Hub hum hyb hyd hyd hyp hys ide ign ima imp imp in- inc Ind ind ine inf inf inf ini ins ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jor jum K c Kep Ker kin kno lab Lam Lan Lap las lat Le lef len lev lig lig lin lin lin liq Lit loc log lon lou LS lun lun Lym M s Mag mag mag mag mag mag maj man Mar mas mas mat May mea mec mel mer mes met met met mic mid mil Min Mir mix mod mod mol mon mor mov mul mur mys nan nat nav nec Nep neu New New NGC nob nom non non nor nos nuc nuc num nut obj obl obs occ oct off oli oni ope opp opt opt orb ord org orp osc out ove oxi P-w pal par par par par Pas pat pej per per per per per per pha Phe pho pho pho phy pin pla Pla pla pla pla plu poi pol pol Pol pol por pos pot Poy pre pre pre pre pri pri pri pro pro pro pro pro pro Psa pul pum Q i qua qua qua qua R A rad rad rad rad rad rad Ram Ran rat rea rea rec rec red red ref ref reg rei rel rel rem rep res res res ret rev Rho Rie ril riv rog Ros rot rul S A Sag sam sat sca sca Sch Sco Sec sec sec seg sel sem sen set Sha sha shi sho sid sig sim sin Sir ske sli Smo soc sof sol sol sol sol sou sou spa spe spe Spe spe sph spi Spi spr sta sta sta sta sta ste ste ste Sto str str sub sub sub suc sun sup sup sup sup sur swa syn syn tac tas tel tem ter tes the the the the thi thr tid til tip ton tor tou tra tra tra tra Tri tri tru tsu tur two Typ UHE ult unc uni uni uni upg ura uti val var vec Vel ver Ver vie Vir vis vis vol W-R war wav wav wea Wei wha wid win WN3 Wol wri xen yok zen zij > >>

Number of Results: 13116 Search : far
Herschel Satellite
  ماهواره‌ی ِ هرشل   
mâhvâre-ye Herschel

Fr.: Satellite Herschel   

A European Space Agency (ESA) mission to perform imaging photometry and spectroscopy in the → far infrared and → submillimeter regions of the electromagnetic spectrum, covering approximately the 55-672 µm range. In fact Herschel is the first space facility dedicated to these wavelength ranges. It carries a 3.5 m diameter passively cooled mirror. The science payload complement - two cameras/medium resolution spectrometers (PACS and SPIRE) and a very high resolution → superheterodyne spectrometer (HIFI) - are housed in a superfluid helium cryostat. Herschel was launched on 14 May 2009, together with the → Planck Satellite. Its observing position lies at the L2 → Lagrangian point, some 1.5 million km from Earth. Herschel is designed, among other things, to study the formation of galaxies in the early Universe, and to investigate the formation of stars and their interaction with the → interstellar medium.

Herschel; → satellite.

Herschelian telescope
  تلسکوپ ِ هرشل، دوربین ~   
teleskop-e Herschel, durbin-e ~

Fr.: télescope de Herschel   

A → reflecting telescope in which the → primary mirror is tilted so that light is focused near one side of the open end of the tube. The → eyepiece then picks up this light directly, avoiding light loss from reflection by a → secondary mirror. The drawback is → astigmatism, unless the → focal ratio is large. Herschel used this design in his giant 48-inch instrument.

Herschel; → telescope.

hertz (Hz)
  هرتز   
hertz (#)

Fr.: hertz   

The SI unit of frequency, defined as a frequency of 1 cycle per second.

After Heinrich Rudolf Hertz (1857-1894), the German physicist, who made several important contributions to the study of electromagnetism.

Hertz experiment
  آزمایش ِ هرتز   
âzmâyeš-e Hertz (#)

Fr.: expérience de Hertz   

A laboratory experiment carried out by Heinrich Hertz in 1888 to generate and detect → electromagnetic waves for the first time. It involved a high voltage power source, consisting of two → capacitors, each provided with a conducting rod. The rods were separated by a small → spark gap and connected to an → induction coil. When the electrodes were raised to a sufficiently high → potential difference, a spark passed across the gap, and an oscillating discharge took place. A group of waves with a wavelength of a few meters were emitted at each discharge. A wire loop provided with a detecting spark gap, held away from the oscillating sparks, produced sparks upon arrival of the oscillating electric and magnetic fields.

hertz (Hz); → experiment.

hertz to meter conversion
  هاگرد ِ هرتز به متر   
hâgard-e hertz bé metr

Fr.: conversion hertz / mètre   

frequency to wavelength conversion.

hertz; → meter; → conversion.

Hertzian oscillator
  نوشگر ِ هرتزی   
navešgar-e Hertzi

Fr.: oscillateur hertzien   

An electrical system used for the production of → electromagnetic waves. It consists of two equal → capacitors connected to two electrodes with a → spark gap between the electrodes. The system is connected to an → induction coil. When the induction coil is activated, electromagnetic waves are generated across the spark gap. See also → Hertz experiment.

hertz (Hz); → oscillator.

Hertzsprung gap
  گاف ِ هرتسپرونگ   
gâf-e Hertzsprung

Fr.: trou de Hertzsprung   

A region of the → Hertzsprung-Russell diagram, between the → main sequence and the → giant branch, occupied by very few stars. It corresponds to a very short period in stellar evolution.

Named after the Danish astronomer Ejnar Hertzsprung (1873-1967), who first noticed this phenomenon; → gap

Hertzsprung-Russell diagram
  نمودار ِ هرتسپرونگ-راسل   
nemudâr-e Hertzsprung-Russell (#)

Fr.: diagramme de Hertzsprung-Russell   

A display of stellar properties using a plot of → effective temperature (or instead → color or → spectral type) along the abscissa versus → luminosity (or → absolute magnitude). The temperature is plotted in the inverse direction, with high temperatures on the left and low temperatures on the right. On the diagram the majority of stars are concentrated in a diagonal strip running from upper left to lower right, i.e. from high temperature-high luminosity → massive stars to low temperature-low luminosity → low-mass stars. This feature is known as the → main sequence. This is the locus of stars burning hydrogen in their cores (→ proton-proton chain). The lower edge of this strip, known as the → zero age main sequence (ZAMS), designates the positions where stars of different mass first begin to burn hydrogen in their cores. Well below the main sequence there is a group of stars that, despite being very hot, are so small that their luminosity is very small as a consequence. These are the class of → white dwarfs. These objects represent old and very evolved stars that have shed their outer layers to reveal a very small but extremely hot inner core. They are no longer generating energy but are merely emitting light as they cool (→ white dwarf cooling track). Stars with high luminosities but relatively low temperatures occupy a wide region above the main sequence. The majority of them have used up all the hydrogen in their cores and have expanded and cooled as a result of internal readjustment. Called → red giants, they are still burning helium in their cores (→ helium burning, → carbon burning). There are also stars with very high luminosities, resulting from their enormous outputs of energy, because they are burning their fuel at a prodigious rate. These are the → supergiants. They can be hot or cool, hence blue or red in color. Same as → H-R diagram.
See also:
asymptotic giant branch, → blue horizontal branch star, → extreme horizontal branch star, → field horizontal branch star, → Hayashi track, → horizontal branch, → post-asymptotic giant branch star, → red giant branch, → supra-horizontal branch star, → zero age horizontal branch star, → Humphreys-Davidson limit.

Named after the Danish Ejnar Hertzsprung (1873-1967) and the American Henry Norris Russell (1877-1957). However, the first H-R diagram was published not by Hertzpurung neither Russell, but by a PhD student of Karl Schwarzschild at Göttingen. The student was Hans Rosenberg (1879-1940), who in 1910 published the diagram for stars in the → Pleiades (Astronomische Nachrichten, Vol. 186 (4445), p. 71, 1910). Although Hertzpurung had a very preliminary diagram in 1908, his first proper diagram was published in 1911. Likewise, Russell published his version only in 1915 with the better and more numerous data then available (Nielsen, A.V., 1969, Centaurus 9, 219; Valls-Gabaud, D., 2002, Observed HR diagrams and stellar evolution, ASP Conf. Proceedings, Vol. 274. Edited by Thibault Lejeune and João Fernandes); → diagram.

Hesperian era
  دوران ِ هسپریسی   
dowrân-e hesperisi

Fr.: ère hespérienne   

The Martian geologic era after the Noachian Era which lasted from about 3500 million to 2500 million years ago. During this period Martian climate began to change to drier, dustier conditions. Water that flowed on the Martian surface during the Noachian Era may have frozen as underground ice deposits, and most river channels probably experienced their final flow episodes during this era. → Noachian era; → Amazonian era.

Named after the Martian plains of Hesperis; → era.

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.

<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer aga air Alf Alg alk Alp alt alu amm ana And ang ani ano ant ant Ap apo app app Aqu Arc arg arr asc ass ast ast asy atm ato att aur aut axi B-m bad Bal bar bar Bay Bed ber Bet bif bim bin bio bis bla ble blu Bod Bol bor bou Bra Bre bro bul C-t Cal Cam can car Car Cas cat cav cel cen cer Cha cha Cha che chl Cir cir cir Cla cli clo clu co- coc coh col col col Com com com com com com com com Com con con con con con con con con con con con con coo Cor Cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl Dan dat Dav de- Deb dec dec dee def deg del Den den der det deu dew dic dif dif dil Dip dir dis dis dis dis dis diu dod Dop dou Dra dua dus dwa dyn DZ Ear ecc eco edi EHB Ein ela ele ele ele ele ell eme emp end Eng ent epi equ equ era ESP eth Eur evi exa exc exe exi exp exp ext ext ext fac fal far fec Fer fer fie fin fir fis fla Flo flu fog for for Fou fra fre fre Fro fun G s Gal gal gal Gar gau geg gen geo geo geo ger gla gly gra gra gra gra gra Gre gro GYR Had Hal hap Har HD hea hel hel Hen Her hex hig Hil hol Hoo hor hou Hub hum hyb hyd hyd hyp hys ide ign ima imp imp in- inc Ind ind ine inf inf inf ini ins ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jor jum K c Kep Ker kin kno lab Lam Lan Lap las lat Le lef len lev lig lig lin lin lin liq Lit loc log lon lou LS lun lun Lym M s Mag mag mag mag mag mag maj man Mar mas mas mat May mea mec mel mer mes met met met mic mid mil Min Mir mix mod mod mol mon mor mov mul mur mys nan nat nav nec Nep neu New New NGC nob nom non non nor nos nuc nuc num nut obj obl obs occ oct off oli oni ope opp opt opt orb ord org orp osc out ove oxi P-w pal par par par par Pas pat pej per per per per per per pha Phe pho pho pho phy pin pla Pla pla pla pla plu poi pol pol Pol pol por pos pot Poy pre pre pre pre pri pri pri pro pro pro pro pro pro Psa pul pum Q i qua qua qua qua R A rad rad rad rad rad rad Ram Ran rat rea rea rec rec red red ref ref reg rei rel rel rem rep res res res ret rev Rho Rie ril riv rog Ros rot rul S A Sag sam sat sca sca Sch Sco Sec sec sec seg sel sem sen set Sha sha shi sho sid sig sim sin Sir ske sli Smo soc sof sol sol sol sol sou sou spa spe spe Spe spe sph spi Spi spr sta sta sta sta sta ste ste ste Sto str str sub sub sub suc sun sup sup sup sup sur swa syn syn tac tas tel tem ter tes the the the the thi thr tid til tip ton tor tou tra tra tra tra Tri tri tru tsu tur two Typ UHE ult unc uni uni uni upg ura uti val var vec Vel ver Ver vie Vir vis vis vol W-R war wav wav wea Wei wha wid win WN3 Wol wri xen yok zen zij > >>