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 AGB air Alf Alg all alp alt AM amo ana And ang ani ano Ant Ant apa apo app app Ara Arc ari Arr ash ass ast ast asy atm ato att aut ave axi Bab bal Bal bar bar bea Bek Bes bia Big bin bin bip biv bla bli blu Boh Bol Bos bou bra bri bro buo cal cal can cap car Car cat cat CCD Cen cen CH cha cha che Che chr cir cir cit cla clo clo clu Coa coe 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 Cop Cor cor cor cos cos cou cou Cow cre cri cro cry cur cya Cyg dan dar dat de- deb dec dec ded def deg del dem den dep des det dev dia dif dif dih dio Dir dis dis dis dis dis dis DO don dou dow dro dur dwa dyn Dys ear ebb ecl edg egg Ein Ela ele ele ele ele ell eme emp enc eng ent epi equ equ equ esc eth Eur Eve exa exc exe exi exp exp ext ext ext fac fal far fed Fer fer fie fin fir fis fla flo flu fol for for fou fra fre Fre fro fut G-t gal gal gam gas Gau Gem gen geo geo geo gia Gli Gol gra gra gra gra gre gri gui H I Hag hal har hat He- hea hel Hel her Hes hie hig his hom hor hot Hub Hug hur hyd hyd hyg hyp ice ide ima Ima imp imp inc inc ind ine inf inf inf ing inn ins ins int int int int int int int int inv Io ion iro isl iso iso Jac jet jud jur Kel Kep kil Klo Kui Lag lam Lap Lar lat law lea len lep Lib lig lim lin lin Lio lit loc LOF lon Lor low lum lun Lup Lyo mac mag mag mag mag mag mai man Mar mas mas mat Max mea mec Meg Mer Mer met met Met mic Mid Mil min Mir mit mod mod mol mon Mor mou mul mul mys nan Nat nau nec neo neu nev New NGC no nom non non nor not nuc nuc num nut obj obs obs occ ocu oft ome Oor ope opp opt opt orb ord ori ort osc out ove oxi pai pan par par par par pas pea pen per per per per Per per pha phi pho pho pho phy pio Pla pla pla pla Pla plu Poi pol pol pol poo pos pos pot pra pre pre pre pre pri pri pro pro pro pro pro Pro pro pse pul pur qua qua qua qua que rac rad rad rad rad rad rad ran rar ray rea rea rec rec red red ref ref reg rel rel rel ren res res res res ret rev Ric rig rin roc roo rot rot Rus Sac sal sat sca sca Sch sci Scu sec sec Sed sel Sel sen ser Sex Sha she sho sid sig sil sim sin siz sla Sma sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spi spr squ sta sta sta sta ste ste ste Sto Str str str sub sub suc sun sup sup sup sup sur swa syn syn tab tar tek tem ter tes the the the the Tho thr tid tim Tis Too Tor tra tra Tra tra tra tri tri tru Tul tur two Typ ult un- und uni uni unk upp Urc utt val var vec vel ver vib vio vir vis voi vor wan wat wav wax wea Wei whi Wil win WN9 wor X-r yel you zer zod > >>

Number of Results: 13048 Search : far
utterance
  واپش   
vâpeš

Fr.: parole, déclaration   

1) An act of uttering; a spoken word, statement, or vocal sound.
2) Something uttered; a word or words uttered; a cry, animal's call, or the like.
3) Linguistics: Any speech sequence consisting of one or more words and preceded and followed by silence: it may be coextensive with a sentence (Dictionary.com).

utter; → -ance.

uvby system
  راژمان ِ uvby   
râžmân-e uvby

Fr.: système photométrique uvby   

A four-color stellar → photometric system devised by B. Strömgren. It is based on measurements in the ultraviolet (3500 Å), violet (4100 Å), blue (4670 Å), and yellow (5470 Å) regions of the spectrum. The filters bandwidths are 340, 200, 160, and 240 Å respectively. Also known as Strömgren four-color photometry.

u, v, b, and y referring to ultraviolet, violet, blue, and yellow respectively; → system.

UX Ori star
  ستاره‌ی ِUX شکارگر   
setâre-ye UX Šekârgar

Fr.: étoile UX Ori   

A star that shows large irregular brightness variations and belongs to the Herbig Ae/Be family, i.e. pre-main sequence stars of intermediate mass. Typically a decrease of 2-3 magnitudes in the visible occurs for a few days to a couple of weeks. Current theories explain this behavior as being an obscuration of the central star by orbiting dust clouds, as well as contribution to the total luminosity by unsteady accretion onto the central star. Also called UXOr.

U and X letters of alphabet, Ori, → Orion; → star.

V2052 Ophiuchi
  V2052 مار‌افسا   
V2052 Marafsâ

Fr.: V2052 Oph   

A hot star of → apparent visual magnitude V = 5.82 lying in the constellation → Ophiuchus, also known as HR 6684, HD 163472, and HIP 87812. V2052 Oph is of → subgiant  → spectral type B2 IV-V and belongs to the family of magnetic → Beta Cephei → pulsators. It has a luminosity of 620 Lsol, a radius of 6.83 Rsol and lies about 830 → light-years away. Three stellar pulsation modes have been detected and studied from ground-based spectroscopy and multi-color photometry. Its magnetic field was deduced to be → dipolar dipolar with a strength of ~ 400 G, inclined 35° to the rotation axis. The star's → convective overshooting region is small, with no extra mixing in spite of the relatively large rotational velocity. This clearly illustrated the effect of the magnetic field: the inhibition of chemical mixing processes by the magnetic field. This result is in agreement with theoretical criteria, which predict that a surface magnetic field of ~ 70 G is sufficient to limit the overshooting in this star. V2052 Oph is now considered as a prime example of what magneto-asteroseismology can achieve (Neiner et al., 2012, A&A, 537, A148).

variable star designation.

vacuum
  خلاء   
xala' (#)

Fr.: vide   

1) A space completely empty of matter but not achievable in practice on Earth.
2) A state of lowest energy in a → quantum field theory.

L. vacuum "an empty space, void," noun use of neuter of vacuus "empty," related to vacare "to be empty."

Xala' loan from Ar.

vacuum birefringence
  دوشکست ِ دوخلأیی   
došekast-e jala'i

Fr.: biréfringence du vide   

A highly → magnetized vacuum behaving as a prism for the propagation of light, as predicted by → quantum electrodynamics (QED). Attempts to detect this phenomenon in the laboratory have not yet succeeded in the 80 years since it was predicted (Heisenberg & Euler, 1936, Z. Physik, 98, 714). This effect can be detected only in the presence of enormously strong → magnetic fields, such as those around → neutron stars. Owing to the large inferred magnetic fields (B ~ 1013 G, → gauss), radiation from these sources is expected to be substantially polarized, independently of the mechanism actually responsible for the → thermal emission. The strongest magnetic field so far created in a laboratory is less than 106 G lasting only for several tens of milliseconds. A large observed → polarization degree is, however, expected only if QED polarization effects are present in the magnetized vacuum around the star. The detection of a strongly → linearly polarized signal would therefore provide the observational evidence of QED effects in the strong-field regime. Recently a team of astrophysicists (Mignani et al. 2016, arXiv/1610.08323) have detected → linear polarization toward the neutron star RXJ1856.5-3754 (at a significant degree of around 16%). This finding is likely due to the boosting effect of vacuum birefringence occurring in the area of empty space surrounding the neutron star.

vacuum; → birefringence.

vacuum chamber
  اتاقک ِ خلاء   
otâqak-e xala'

Fr.: chambre à vide   

An enclosure from which air is removed.

vacuum; → chamber.

vacuum energy
  کاروژ ِ خلاء   
kâruž-e xala'

Fr.: énergie du vide   

In particle physics the lowest energy allowed by field quantization when all fields are in their → ground states. Vacuum energy is predicted to arise from → virtual particles that fluctuate in and out of existence, as manifested by the → Casimir effect. The cosmological → dark energy is postulated to be related to vacuum fluctuations. There is however an enormous discrepancy with the predictions of quantum field theory. In this theory the value of vacuum energy density is expected to be roughly of the order ρvEmax4, where Emax is the maximum energy at which the field theory is valid. At energies of the order of the → Planck energy, EPl≅ 1019 GeV, vacuum energy might be roughly: ρvEPl4≅ 1076 GeV4. On the other hand, the vacuum energy density in standard cosmological model is given by: ρΛ = ΩΛcrit, where ΩΛ is the → density parameter for the → cosmological constant and ρcrit is the → critical density. More explicitly, ρΛ = ΩΛ . 3 H2/(8πG). Using present-day values of ΩΛ (0.7) and H (70) leads to ρΛ = 10-46 GeV4. Therefore, the discrepancy between the prediction and the observed value is 122 orders of magnitude.

vacuum; → energy.

vacuum polarization
  قطبش ِ خلاء   
qotbeš-e xala'

Fr.: polarisation du vide   

A quantum field theory a process in which an electromagnetic field gives rise to virtual electron-positron pairs that in turn exert electromagnetic fields of their own, in a manner similar to classical dielectric polarization.

vacuum; → polarization.

vague
  گرنگ   
gereng

Fr.: vague   

1) Not clearly or explicitly stated or expressed.
2) Indefinite or indistinct in nature or character, as ideas or feelings.
3) Not definitely established, determined, confirmed, or known; uncertain (Dictionary.com). → ambiguous, → nebulous, → indefinite, → fuzzy, → unclear.

M.E., from M.Fr. vague "empty, vacant; wild, uncultivated; wandering," from L. vagus "wandering, rambling," of unknown origin.

Gereng, from Kalidari gereng "wandering," Kurd. (Kurmanji) garin, (Sorani) garân "to wander," Dehxodâ gereng "shattered;" ultimately from Proto-Ir. *gar-an-ka-, from *gar- "to turn, to wind" (Cheung 2007).

vague year
  سال ِ گردان، ~ گرنگ   
sâl-e gardân, ~ gereng

Fr.: année vague   

A year of 365 days that overlooks the fraction of less than 0.25 days corresponding to the whole length of the → tropical year. The vague year was used in the → calendars of ancient Egypt, Iran, Mayas, and some other civilizations. Typically the vague year was divided into 12 months of 30 days each plus 5 → epagomenal days.

From annus vagus "wandering year;" → vagueyear.

valence
  ارزایی   
arzâyi

Fr.: valence   

A measure of the number of chemical bonds formed by the atoms of a given element. It represents the relative ability of an atom of an element to combine with other atoms. For example, the valence of O in water, H2O, is 2. Also called valency.

M.E., from O.Fr., from L valentia "strength, worth," from valentem (nominative valens), pr.p. of valere "to be strong."

Arzâyi, noun from arzâ, agent noun/adj. from arzidan "to be worth," arzân "worthy; of small value, cheap," arj "esteem, honour, price, worth" (Mid.Pers. arz "value, worth," arzidan "be worth," arzân "valuable;" Av. arəjaiti "is worth," arəja- "valuable," arəg- "to be worth;" cf. Skt. arh- "to be worth, to earn," árhant- "worthy person;" Gk. alphanein "to bring in as profit," alphein "to ear, obtain;" Lith. algà "salary, pay;" PIE base *algwh- "to earn; price, value").

valence band
  باند ِ ارزایی   
bând-e arzâyi

Fr.: bande de valence   

The range of energy states in the spectrum of a solid crystal which includes the energies of all the electrons binding the crystal together.

valence; → band.

valence electron
  الکترون ِ ارزایی   
elektron-e arzâyi

Fr.: électron de valence   

An electron of an atom lying farthest from the nucleus. Valence electrons are shared when atoms combine to form molecules.

valence; → electron.

valency
  ارزایی   
arzâyi

Fr.: valence   

Same as → valence.

valid
  پای‌مند   
pâymand

Fr.: valide   

Logic: Of an argument, if the premises are true, then the conclusion cannot be denied without contradiction. The truth of the premises logically guarantees the truth of the conclusion.

M.E., from M.Fr. valide, from L. validus "strong, effective," from valere "to be strong."

Pâymand, from pâ, pây "foot; base, foundation, firmness" (Mid.Pers. pâd, pây; Av. pad- "foot;" cf. Skt. pat; Gk. pos, genitive podos; L. pes, genitive pedis; P.Gmc. *fot; E. foot; Ger. Fuss; Fr. pied; PIE *pod-/*ped-) + -mand possession suffix.

validity
  پای‌مندی   
pâymandi

Fr.: validité   

Logic: Of an argument, whether or not the conclusion follows logically from the premises and the allowable syllogisms of the logical system being used.

Quality noun from → valid.

Valles Marineris
  درّه‌های ِ مارینر   
darrehâ-ye Mariner

Fr.: Valles Marineris   

A system of canyons located just south of the Martian equator. The system is about 4000 km long. The central individual troughs, generally 50 to 100 km wide, merge into a depression as much as 600 km wide. In places the canyon floor reaches a depth of 10 km, 6 to 7 times deeper than the Grand Canyon on Earth.

L. Valles Marineris "Mariner's Valleys," named after the Mars orbiter Mariner 9, which discovered the Martian canyon in 1971-72. → valley.

valley
  درّه   
darré (#)

Fr.: vallée   

A long, narrow region of low land between ranges of mountains, hills, or other high areas, often having a river or stream running along the bottom.

M.E. valeie, valey, from O.Fr. valee "valley," from V.L. *vallata, from L. vallis "valley," of unknown origin.

Darré "valley," from Mid.Pers. dar, darrak "ravine, cleft;" cf. Skt. pradará- "cleft."

value
  ارزش   
arzeš (#)

Fr.: valeur   

Math.: Magnitude; quantity; a numerical quantity assigned to a mathematical symbol.

M.E., from O.Fr. value "worth, value," noun use of feminine p.p. of valoir "be worth," from L. valere "be strong, be well, be of value."

Arzeš, verbal noun of arzidan "to be worth," arzân "worthy; of small value, cheap," arj "esteem, honour, price, worth;" Mid.Pers. arz "value, worth," arzidan "be worth," arzân "valuable;" Av. arəjaiti "is worth," arəja- "valuable," arəg- "to be worth;" cf. Skt. arh- "to be worth, to earn," árhant- "worthy person;" Gk. alphanein "to bring in as profit," alphein "to ear, obtain;" Lith. algà "salary, pay;" PIE base *algwh- "to earn; price, value."

<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer AGB air Alf Alg all alp alt AM amo ana And ang ani ano Ant Ant apa apo app app Ara Arc ari Arr ash ass ast ast asy atm ato att aut ave axi Bab bal Bal bar bar bea Bek Bes bia Big bin bin bip biv bla bli blu Boh Bol Bos bou bra bri bro buo cal cal can cap car Car cat cat CCD Cen cen CH cha cha che Che chr cir cir cit cla clo clo clu Coa coe 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 Cop Cor cor cor cos cos cou cou Cow cre cri cro cry cur cya Cyg dan dar dat de- deb dec dec ded def deg del dem den dep des det dev dia dif dif dih dio Dir dis dis dis dis dis dis DO don dou dow dro dur dwa dyn Dys ear ebb ecl edg egg Ein Ela ele ele ele ele ell eme emp enc eng ent epi equ equ equ esc eth Eur Eve exa exc exe exi exp exp ext ext ext fac fal far fed Fer fer fie fin fir fis fla flo flu fol for for fou fra fre Fre fro fut G-t gal gal gam gas Gau Gem gen geo geo geo gia Gli Gol gra gra gra gra gre gri gui H I Hag hal har hat He- hea hel Hel her Hes hie hig his hom hor hot Hub Hug hur hyd hyd hyg hyp ice ide ima Ima imp imp inc inc ind ine inf inf inf ing inn ins ins int int int int int int int int inv Io ion iro isl iso iso Jac jet jud jur Kel Kep kil Klo Kui Lag lam Lap Lar lat law lea len lep Lib lig lim lin lin Lio lit loc LOF lon Lor low lum lun Lup Lyo mac mag mag mag mag mag mai man Mar mas mas mat Max mea mec Meg Mer Mer met met Met mic Mid Mil min Mir mit mod mod mol mon Mor mou mul mul mys nan Nat nau nec neo neu nev New NGC no nom non non nor not nuc nuc num nut obj obs obs occ ocu oft ome Oor ope opp opt opt orb ord ori ort osc out ove oxi pai pan par par par par pas pea pen per per per per Per per pha phi pho pho pho phy pio Pla pla pla pla Pla plu Poi pol pol pol poo pos pos pot pra pre pre pre pre pri pri pro pro pro pro pro Pro pro pse pul pur qua qua qua qua que rac rad rad rad rad rad rad ran rar ray rea rea rec rec red red ref ref reg rel rel rel ren res res res res ret rev Ric rig rin roc roo rot rot Rus Sac sal sat sca sca Sch sci Scu sec sec Sed sel Sel sen ser Sex Sha she sho sid sig sil sim sin siz sla Sma sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spi spr squ sta sta sta sta ste ste ste Sto Str str str sub sub suc sun sup sup sup sup sur swa syn syn tab tar tek tem ter tes the the the the Tho thr tid tim Tis Too Tor tra tra Tra tra tra tri tri tru Tul tur two Typ ult un- und uni uni unk upp Urc utt val var vec vel ver vib vio vir vis voi vor wan wat wav wax wea Wei whi Wil win WN9 wor X-r yel you zer zod > >>