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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<< < -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
metal-rich star
  ستاره‌ی ِ پرفلز   
setâre-ye porfelez

Fr.: étoile riche en métaux   

A star whose → metal content is higher than the → solar metallicity. The stars that harbor → extrasolar planets tend to be considerably more metal-rich than the average → Population I star in the Galactic neighborhood. See also → super-metal-rich star.

metal; → rich; → star.

metalanguage
  متا-زبان   
matâ-zabâb

Fr.: métalangue   

Any language that is used to describe a language. See also → object language.

meta-; → language.

metallic
  فلزی   
felezi (#)

Fr.: métallique   

Of, relating to, or consisting of metal.

metal; → -ic.

metallic hydrogen
  هیدروژن ِ فلزی   
hidrožen-e felezi

Fr.: hydrogène métallique   

A kind of → degenerate matter resulting from hydrogen gas when it is sufficiently compressed to undergo a phase change to liquid or solid state. Metallic hydrogen is thought to be present in compressed astronomical objects, such as the interiors of the solar system planets Jupiter and Saturn. Above the core of these planets (at a temperature of 10,000 degrees and a pressure of 3 million bars) the electrons are squeezed out of the hydrogen atoms and the fluid starts to conduct like a metal.

metallic; → hydrogen.

metallicity
  فلزیگی   
felezigi

Fr.: métallicité   

In a star, nebula, or galaxy, the proportion of the material that is made up of → metals, that is elements heavier than → helium. It is generally denoted by Z. The term "metallicity" is a misnomer used in astrophysics.
1) In practice, the metallicity of stars is usually expressed by the number ratio of → iron atoms to → hydrogen atoms per unit volume, with respect to the solar values: [Fe/H] = log10(NFe/NH)star - log10(NFe/NH)Sun, where NFe and NH are the numbers of iron and hydrogen atoms per unit volume. In fact it is taken to be equal to the iron → abundance with respect to the solar value. The solar logarithmic iron abundance is 7.50 ± 0.04 (Asplund et al. 2009, ARAA 47, 481), with respect to that of hydrogen which, by convention, is 12.00. Stellar metallicity is often expressed in mass fraction. See also → solar metallicity.
2) Nebular metallicity is often defined as the relative abundance of → oxygen: (NO/NH)neb/(NO/NH)Sun, where NO and NH represent the numbers of oxygen and hydrogen atoms per unit volume.

From metallic, from → metal + → -ity.

metallicity distribution function (MDF)
  کریای ِ واباژش ِ فلزیگی   
karyâ-ye vâbâžeš-e felezigi

Fr.: fonction de distribution de métallicité   

A plot representing the number of stars (or systems) per metallicity interval, usually expressed in [Fe/H] (abundance of → iron relative to → hydrogen).

metallicity; → distribution; → function.

metallicity gradient
  زینه‌ی ِ فلزیگی   
zine-ye felezigi

Fr.: gradient de métallicité   

The decrease in the → abundances of → heavy elements in a → disk galaxy as a function of distance from the center. Radial metallicity gradients are observed in many galaxies, including the → Milky Way and other galaxies of the → Local Group. In the case of the Milky Way, several objects can be used to determine the gradients: → H II regions, → B stars, → Cepheids, → open clusters, and → planetary nebulae. The main diagnostic elements are oxygen, sulphur, neon, and argon in photoionized nebulae, and iron and other elements in Cepheids, open clusters, and stars. Cepheids are probably the most accurate indicators of abundance gradients in the Milky Way. They are bright enough to be observed at large distances, so that accurate distances and spectroscopic abundances of several elements can be obtained. Average abundance gradients are generally between -0.03 → dex/kpc and -0.10 dex/kpc, with a a flattening out of the gradients at large galactocentric distances (≥ 10 kpc). The existence of these gradients offers the opportunity to test models of → chemical evolution of galaxies and stellar → nucleosynthesis.

metallicity; → gradient.

metastable state
  حالت ِ متاپایدار   
hâlat-e matâpâydâr

Fr.: état métastable   

An excited state in an atom, which is at the origin of the spectral lines called → forbidden lines. The time duration of the excited state being relatively long, under laboratory conditions the atom cannot pass directly to the ground state by emitting radiation. In the extremely rarefied interstellar medium, however, such highly improbable transitions do occur.

meta-; → stable; → state.

meteor
  شهاب   
šahâb (#)

Fr.: météore   

A streak of light caused when a → meteoroid enters Earth's → atmosphere and becomes incandescent, mostly from → friction with the air at high speed. Meteors are also referred to as shooting stars. Very bright meteors are called → fireball or → bolide. Most of visible meteors arise from particles ranging in size from about that of a small pebble down to a grain of sand, and generally weigh less than 1-2 grams. The brilliant flash of light from a meteor is mainly caused by the → meteoroid's high level of → kinetic energy as it collides with the atmosphere at high speeds (11-72 km/s). The increase in the number of meteors visible toward the end of the night results from the fact that the Earth rotates about its axis in the same direction as it orbits the Sun. This means that the leading edge (morning side) of the Earth encounters more meteoroids than the trailing edge (evening side). In general, 2 to 3 times as many meteors can be seen in the hour or so just before morning twilight, than can be seen in the early evening. Moreover, the numbers of random, or sporadic, meteors vary from season to season, due to the tilt of the Earth on its axis and other factors. See also → meteor shower.

From M.Fr. meteore, from M.L. meteorum (nom. meteora), from Gk. ta meteora "the celestial phenomena," pl. of meteoron, literally "thing high up," neuter of meteoros (adj.) "high up," from → meta- "over, beyond" + -aoros "lifted, hovering in air," related to aeirein "to raise."

Šahâb, from Ar. Šihâb.

Meteor Crater
  لاوک ِ شهاب‌سنگ، کندال ِ ~، ~ آسمان‌سنگ   
lâvak-e šahâbsang, kandâl-e ~, ~ âsmânsang

Fr.: Meteor Crater   

A → meteorite impact crater located about 55 km east of Flagstaff, near Winslow in the northern Arizona desert of the United States. Meteor Crater is about 1,200 m in diameter and some 170 m deep. It is thought to have formed between 20,000 to 50,000 years ago, by the impact of a small → asteroid about 25 m in diameter. Same as → Barringer Crater.

meteor; → crater.

meteor echo
  پژواک ِ شهاب   
pažvâk-e šahâb

Fr.: écho de météore   

The reflection of → radio waves from transmitters located on the ground by a → meteor or by the corresponding trail left behind. When a meteor enters the Earth's upper atmosphere it excites the air molecules, producing a streak of light and leaving a trail of ionization behind it tens of kilometers long. This ionized trail occurs typically at a height of about 85 to 105 km, and may persist for less than 1 second up to several minutes.

meteor; → echo.

meteor shower
  باران ِ شهابی، رگبار ِ ~، تندبار ِ ~   
bârân-e šahâbi, ragbâr-e ~, tondbâr-e ~ (#)

Fr.: averse de météores, pluie de ~   

An increased number of → meteors all appearing to → diverge from the direction of a single point, called → radiant. Meteor showers occur → annually on the same dates, when the Earth crosses through a → meteoroid stream. Meteor showers are named after the → constellation in which the radiant is located. For example, the → Perseids's radiant lies near the top of the constellation Perseus. Most meteor showers are caused by → comets. As a comet orbits the Sun it sheds an icy, dusty → debris stream along its orbit. When the Earth's orbit intersects the dust trail, more meteors are seen as the cometary debris encounters our planet's → atmosphere. In the case of the → Geminids and → Quadrantids, those meteor showers come from the debris scattered by orbiting → asteroids. Typical meteor showers show 15 to 100 meteors per hour at their peak. On very rare occasions, during a → meteor storm, thousands of meteors fall per hour. Prominent meteor showers are: → Quadrantids, → Lyrids, → Eta Aquariids, → Delta Aquariids, → Perseids, → Orionids, → Taurids, → Leonids, → Geminids, → Ursids, → Alpha Capricornids.

meteor; → shower.

meteor storm
  توفان ِ شهابی   
tufân-e šahâbi (#)

Fr.: orage de météorites   

An extremely intense → meteor shower, in which hundreds or even many thousands of → meteors per hour may be observed. During the great → Leonids meteor storm of 1833 an estimated number of about 150,000 meteors fell per hour.

meteor; → storm.

meteoric ionization
  یونش ِ شهاب‌سنگی، ~ ِ آسمان‌سنگی   
yoneš-e šahâbsangi, ~ âsmânsangi

Fr.: ionisation météoritique   

The ionization of air molecules by the heat generated when a meteorite enters the atmosphere.

meteorite, → ionization.

meteorite
  شخانه، شهاب‌سنگ، آسمان‌سنگ   
šaxâné (#), šahâbsang (#), âsmânsang (#)

Fr.: météorite   

An object of → extraterrestrial origin that survives entry through the atmosphere to reach the Earth's surface. → Meteors become meteorites if they reach the ground. See also → stony meteorite, → iron meteorite, → stony-iron meteorite, → chondrite, → micrometeorite , → achondrite, → CAI meteorite, → differentiated meteorite, → undifferentiated meteorite, → Hoba meteorite, → Jilin meteorite, → Martian meteorite, → meteorite flux.

From → meteor + -ite a suffix of nouns.

Šaxâné "metor," may be from šaxudan, šaxânidan "to scratch, to thrust, to assail," as the meteor light scratches the dark night.
Šahâbsang, from šahâb, → meteor, + sang, → stone.
Âsmânsang, from âsmân, → sky, + sang, → stone.

meteorite flux
  شار ِ شخانه‌ای   
šâr-e šaxâne-yi

Fr.: flux de météorites   

The total mass of extraterrestrial objects that land on Earth during a given time period. The meteorite flux is currently estimated to be about 107 to 109 kg yr-1. Much of this material is dust-sized objects called → micrometeorites.

meteorite; → flux.

meteoritic
  شخانه‌ای، شهاب‌سنگی   
šaxâne-yi, šahâbsangi (#)

Fr.: météoritique   

Of or pertaining to a → meteorite.

From → meteorite + → -ic.

meteoritic abundance
  فراوانی ِ شخانه‌ای، ~ شهاب‌سنگی   
farâvâni-ye šaxâne-yi, ~ šahânsangi

Fr.: abondance météoritique   

The abundance of a chemical element as derived from meteorites. Meteoritic abundances measured from carbonaceous → CI chondrites are believed to represent → protosolar abundances.

meteoritic; → abundance.

meteoritic impact
  برخورد ِ شخانه‌ای   
barxord-e šaxâne-yi

Fr.: impact météoritique   

A striking of a meteorite against another body, especially the solar system planets or satellites.

meteoritic; → impact.

meteoritics
  شخانیک، شهاب‌سنگ‌شناسی، شهاب‌سنگیک   
šaxânik, šahâbsangšenâsi, šahâbsangik

Fr.: météoritiqu   

The science or study of meteorites.

meteorite + → -ics.

<< < -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 > >>