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
Hartle-Hawking initial state
  استات ِ آغازین ِ هارتل-هاؤکینگ   
estât-e âqâzin-e Hartle-Hawking

Fr.: état initial de Hartle-Hawking   

A proposal regarding the initial state of the → Universe prior to the → Planck era. This → no boundary hypothesis assumes an imaginary time in that epoch. In other words, there was no real time before the → Big Bang, and the Universe did not have a beginning. Moreover, this model treats the Universe like a quantum particle, in an attempt to encompass → quantum mechanics and → general relativity; and attributes a → wave function to the Universe. The wave function has a large value for our own Universe, but small, non-zero values for an infinite number of other possible, parallel Universes.

Hartle, J., Hawking, S., 1983, "Wave function of the Universe," Physical Review D 28; → initial; → state.

Hartley band
  باند ِ هارتلی   
bând-e Hartley

Fr.: bande de Hartley   

A band in the → absorption spectrum of → ozone (O3) extending in the → ultraviolet from 200 nm to 300 nm. It is stronger than the → Huggins band. See also: → Hartley band.

W. N. Hartley, J. Chem. Soc. 39, 111 (1881).

Hartmann test
  آزمون ِ هارتمان   
âzmun-e Hârtman (#)

Fr.: test de Hartmann   

A way of testing the quality of optical systems. In this method, incident rays from a point source are isolated by small holes in an opaque screen located close to the lens or mirror under test. Photographic plates are inserted into the beam within and beyond the focal region. The black dots on the exposed plates, which reveal differences of optical focus in the various zones of the lens or mirror, are analyzed to yield the objective's figure. → Shack-Hartmann wavefront sensor.

Named after the German astronomer Johannes Hartmann (1865-1936), who developed the method. → test.

hartree
  هارتری   
hartree

Fr.: hartree   

A unit of energy used in atomic and molecular physics; symbol Ha or Eh. It is defined as: 1 Ha = mee4/(4ε02ħ), where me is the mass of electron, e its charge, ε0 the → permittivity of vacuum, and ħ → reduced Planck's constant. Its value is 2 → rydbergs, or 4.3597 x 10-18 → joule, or 27.213 → electron-volts.

Named for the British physicist and mathematician Douglas R. Hartree (1897-1958).

Harvard classification
  رده‌بندی ِ هاروارد   
radebandi-ye Hârvârd (#)

Fr.: classification de Harvard   

A classification of stellar spectra published in the Henry Draper catalogue, which was prepared in the early twentieth century by E. C. Pickering and Miss Annie Canon. It is based on the characteristic lines and bands of the chemical elements. The most important classes in order of decreasing temperatures are as follows: O, B, A, F, G, K, M.

Harvard, named for John Harvard (1607-1638), the English colonist, principal benefactor of Harvard College, now Harvard University. → classification

harvest
  ۱) خرمن؛ ۲) خرمن کردن، ~ برداشتن   
1) xarman; 2) xarman kardan, ~ bardâštan

Fr.: 1) moisson, récolte; 2) récolter   

1a) The gathering of a ripened → crop.
1b) (Agriculture) the crop itself or the yield from it in a single growing season.
2) To gather or reap (a ripened crop) from (the place where it has been growing) (TheFreeDictionary).

M.E. hervest, from O.E. hærfest "autumn;" cognate with Du. herfst, Ger. Herbst "autumn"); PIE *(s)kerp- "to gather, pluck, harvest," from *(s)ker- "to cut" (cf. Skt. krpāna- "sword, knife;" Gk. karpos "fruit;" L. carpere "to cut, divide, pluck;" Av. karət- "to cut," Mod.Pers. kârd "knife," as below).

Xarman, ultimately from *xramana-, from *xram- "to thresh;" cf. Ormuri šraməd, Parâci khamör, Yidgha xurom, xuräm; Nuristâni Kati kram- "to thresh;" Skt. kram- "to stride out, to go" (H. W. Bailey, 1979).

harvest moon
  ماه ِ خرمن‌برداری   
mâh-e xarman bardâri

Fr.: lune de moisson   

The → full moon that appears closest in time to the → autumnal equinox.

harvest; → moon.

hatch
  ۱) لاچیدن؛ ۲) لاچش؛ دریچه   
1) lâcidan; 2) lâceš; daricé

Fr.: 1) éclore; 2) éclosion; volet   

1) (of an egg) To open and produce a young animal; emerge from its egg.
2a) The act or process of hatching.
2b) A small opening in a wall that serves as a doorway or window. → dome hatch.

1) M.E. hachen "to produce young from eggs by incubation," probably from an unrecorded O.E *hæccan, of unknown origin, related to M.H.G., Ger. hecken "to mate" (used of birds).
2) M.E. hacche, O.E. hæcc "fence, half-gate;" cf. M.H.G. heck, Du. hek "gate, railing."

1) Lâcidan, from Tabari lâc "open, separated, wide aprat" (lâc hâytan "to split, to crack," lâc bazoən "to split, to tear"), may be from Proto-Ir. *rauj "to break, burst;" cf. Av. (+*fra-) fra.uruxti- "destruction;" Khotanese *rrus- "to burst, break;" Baluchi ruj- "to break open;" Bartangi, Oroshori ruj-/ruxt- "to dig;" Skt. roj- "to break, break open;" Pali luki- "part;" L. lugere "to mourn, grieve;" Armenian lucanem "I break up."
2) Daricé, from dar, → door, + -cé diminutive suffix.

Hatsya
  هتسیا   
Hatsya

Fr.: Hatsya   

The → component Aa of the → multiple star system  → Iota Orionis,. The name was approved in 2016 by the IAU Working Group on Star Names (WGSN).

Hatsya, of unknown origin.

Haumea
  هاؤمءا   
Haumea

Fr.: Hauméa   

A → dwarf planet located beyond → Neptune's orbit (→ trans-Neptunian object). Haumea is roughly the same size as → Pluto. It spins on its axis once every four hours, making it the fastest spinning known large object in the → solar system. It has two known moons, called Hi'aka and Namaka. Observations from multiple Earth-based observatories of Haumea passing in front of a distant star indicate the presence of a ring with a width of 70 km and radius of about 2,287 km. The ring is coplanar with both Haumea's equator and the orbit of its satellite Hi'aka. The → occultation by the main body indicates an oblong shape for Haumea with axes of about 2,322 × 1,701 × 1,138 km. In other words, along one direction, Haumea is significantly longer than → Pluto, while in another direction it has an extent very similar to Pluto, while in the third direction is much smaller. Haumea's orbit sometimes brings it closer to the Sun than Pluto, but usually Haumea is further (Ortiz et al., 2017, Nature 550, 219, doi:10.1038/nature24051).

Named for the Hawaiian goddess of childbirth and fertility (temporary designation 2003 EL61). Its moons are named for daughters of Haumea.

Hawking radiation
  تابش ِ هاؤکینگ   
tâbeš-e Hawking (#)

Fr.: rayonnement de Hawking   

The radiation produced by a → black hole when → quantum mechanical effects are taken into account. According to quantum physics, large fluctuations in the → vacuum energy occurs for brief moments of time. Thereby virtual particle-antiparticle pairs are created from vacuum and annihilated. If → pair production happens just outside the → event horizon of a black hole, as soon as these particles are formed they would both experience drastically different → gravitational attractions due to the sharp gradient of force close to the black hole. One particle will accelerate toward the black hole and its partner will escape into space. The black hole used some of its → gravitational energy to produce these two particles, so it loses some of its mass if a particle escapes. This gradual loss of mass over time means the black hole eventually evaporates out of existence. See also → Bekenstein formula, → Hawking temperature.

Named after the British physicist Stephen Hawking (1942-2018), who provided the theoretical argument for the existence of the radiation in 1974; → radiation.

Hawking temperature
  دمای ِ هاؤکینگ   
damâ-ye Hawking

Fr.: température de Hawking   

The temperature inferred for a → black hole based on the → Hawking radiation. For a → Schwarzschild black hole, one has TH = ħc3/(8πGMk) where ħ is the → reduced Planck's constant, c is the → speed of light, G is the → gravitational constant, M is the mass, and k is → Boltzmann's constant. The formula can approximately be written as: TH≅ 6.2 x 10-8 (Msun/M) K. Thus radiation from a solar mass black hole would be exceedingly cold, about 5 x 107 times colder than the → cosmic microwave background. Larger black holes would be colder still. Moreover, smaller black holes would have higher temperatures. A → mini black hole of mass about 1015 g would have TH≅ 1011 K.

Hawking radiation; → temperature.

Hayabusa2
  هایابوسا۲   
Hayabusa2

Fr.: Hayabusa2   

A Japanese → asteroid sampling mission devoted to the study of → Ryugu. It was launched on December 3, 2014 and successfully arrived at the asteroid on June 27, 2018. The Hayabusa2 mission includes four rovers with various scientific instruments. On September 21, 2018 the first two of these rovers, MINERVA-II robots, which hop around the surface of the asteroid, were released from Hayabusa2. This marked the first time a mission has completed a successful landing on a fast-moving asteroid body. This was followed later by the deployment of MASCOT (Mobile Asteroid Surface Scout), a lander developed by the German space agency DLR in partnership with the French Center for Spatial Studies (CNES). It carried four instruments and with its 16 h lifetime battery collected data on the surface structure and mineralogical composition, the thermal behaviour and the magnetic properties of the asteroid. Hayabusa2 is expected to leave Ryugu with the collected samples in late 2019 and return to Earth in 2020.

Hayabusa "peregrine falcon" in Japanese.

Hayashi forbidden zone
  زنار ِ بژکم ِ هایاشی   
zonâr-e baſkam-e Hayashi

Fr.: zone interdite de Hayashi   

The region to the right the → Hayashi track, representing objects that cannot be in → hydrostatic equilibrium. Energy transport in these objects would take place with a → superadiabatic temperature gradient.

Hayashi track; → forbidden; → zone.

Hayashi phase
  فاز ِ هایاشی   
fâz-e Hayashi

Fr.: phase de Hayashi   

A period in the → pre-main sequence evolution of a low mass star during which the star has negligible nuclear energy production and low internal temperature. Hence energy transport inside the star takes place dominantly through → convection. The star contracts homologously and evolves in the → H-R diagram along the → hayashi track with decreasing → luminosity and nearly constant → effective temperature. The time taken by a star of mass M* to contract to radius R* along a Hayashi track is of the order of the → Kelvin-Helmholtz time: tKH = 107(M*/Msun)2/(R*/Rsun)3 yr.

Hayashi track; → phase.

Hayashi temperature
  دمای ِ هایاشی   
damâ-ye Hayashi

Fr.: température de Hayashi   

The minimum → effective temperature required for a → pre-main sequence star of given mass and radius to be in → hydrostatic equilibrium. This temperature delimits the boundary of the → Hayashi forbidden zone.

Hayashi track; → temperature.

Hayashi track
  تر ِ هایاشی   
tor-e Hayashi

Fr.: trajet de Hayashi   

The path on the → Hertzsprung-Russell diagram that is followed by a fully → convective  → pre-main sequence star to reach the → zero-age main sequence. Hayashi tracks for → low-mass stars are near vertical. At higher masses, stars become increasingly radiative as they contract and the Hayashi tracks are almost horizontal.

Named after the Japanese astrophysicist Chushiro Hayashi (1920-2010), who published his paper in 1961 (PASJ 13, 450); → track.

hazard
  آپه   
âpé

Fr.: hasard, risque, danger   

1) A danger that one can foresee but cannot avoid.
2) Something causing unavoidable danger, peril, risk, or difficulty.
3) The absence or lack of predictability; chance; uncertainty (Dictionary.com).

M.E. hasard, from O.Fr. hasard, hasart "game of chance played with dice," possibly from Sp. azar "an unfortunate card or throw at dice," postulated to derive from Ar. az-zahr "the die," but this etymology is controversial.

Âpé, from Av. au-pat-, "to fall down, off," from pat- "to fall, fly;" Proto-Ir. *pat- "to fall; fly; rise;" related to Pers. oftâdan "to fall; to befall; to happen," → fall. Pers. âfat "blight, pest, curse," may belong to this family.

hazardous
  آپه‌ناک   
âpénâk

Fr.: dangereux   

1) Full of risk; perilous; risky.
2. Dependent on chance (Dictionary.com).

Adj. from → hazard.

haze
  نزم   
nezm (#)

Fr.: brume sèche   

A phenomenon where fine particles of → dust and/or → smoke suspended in the → atmosphere near Earth reduce the → visibility by → scattering light.

Maybe from M.E. *hase, O.E. hasu, variant of haswa "ashen, dusky."

Nezm "mist, fog, vapor."

<< < -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 > >>