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 r abe abs abs acc acc acc act act ada adi adu aff age alc Alf ali all alp alt ama amp ana ang ang ann ano ant ant ape apo app aps arc Arg ari art ass ast ast ast atm ato att aur aut axi B r bac Bal Bar Bar Bay bec Ber Bet Bie bij bin bio bis bla bla blu blu bol Bor bou Bra bre bro Bug C-s cal Cam can car Car Cas cat cav cel cen cer Cha cha cha che cho cir cir cir 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 coo cor cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl dar dat daw de- Deb dec dec dee def deg del Den dep der det deu dew dic dif dif dil dip dir dis dis dis dis dis div dog Dop dou dra dua dus dwa dyn e-m ear ecl eco eff ein Ein elb ele ele ele ele Els emi emp ene enr env epi equ equ Eri est Euc eva evo exc exc exh exo exp exp ext ext f-n Fah fam fau fee Fer fib fil fin fir fix fle flu foc for for for fra fre fre fri fun fuz gal gal gal Gan gau GCN gen geo geo geo geo Gl glo gra gra gra gra gra gre gro GW1 hab hal han HAR haz hea hel hel Hen Her heu Hig Hil hol hop hor hou Hub Hum Hyd hyd hyd hyp hys ide ign ima imp imp inc inc ind ine inf inf inf inh INP ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jos Jun K2 Kep key kin Kol lag lam Lan lar las lav lea leg len lev lig lim lin lin lin lis lob loc log lor low lum lun lun Lym Mac mag mag mag mag mag mai Mal mar mas mas mat max mea mea mee Men mer met met met mic mid Mil min Mir mix mod mod mol mon Mor mou mul muo mys nan nat nav nec Nep neu New New NGC nob nom non non nor not nuc nuc num Nyq obj obs obs oce oen OH omn opa ope opt opt opt orb ord Ori ort osc out ove oxy pal pan par Par par par pas pea Pen per per per per per pet pha pho pho pho phy pie Pit Pla pla pla pla ple Poi pol pol pol pol pop pos pos pow pre pre pre Pre pri pri pri pro pro pro pro pro pro Pro pub pul pyr qua qua qua qua Qui rad rad rad rad rad rad ram ran rat rea rec rec rec red ref ref reg reg rel rel rem rep res res res ret rev rho Rie rim riv rol Ros rot rul S a Sah san Sat sca Sch Sch scr sec sec sec sei sel sem sep set sha she sho sid sig sil sim sin sit sky slu sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spl spr sta sta sta sta sta ste ste sti sto str str sub sub sub sug sun sup sup sup sup sur syl syn sys tal Tay tel ten ter tex the the the thi tho thu tid tim tod top tot tra tra tra tra tri tri tro tru tur twi Typ UFO ult unc uni uni uni upg ura uti val var vec vel ver ver vig vir vis voc von wak Was wav wax wea wei whi Wie win WN6 wom X-r yel you zer zod > >>

Number of Results: 12948 Search : far
protoplanetary disk
  گرده‌ی ِ پوروا-سیاره‌ای   
gerde-ye purvâ-sayyâreyi

Fr.: disque protoplanétaire   

A → circumstellar disk of gas and dust surrounding a → pre-main sequence star from which planetary systems form. Protoplanetary disks are remnants of → accretion disks which bring forth stars. Typically, their sizes are ~100-500 AU, masses ~10-2 solar masses, lifetimes ~106-107 years, and accretion rates ~10-7-10-8 solar masses per year. According to the standard theory of planet formation, called core accretion, planets come into being by the growth of → dust grains which stick together and produce ever larger bodies, known as → planetesimals. The agglomeration of these planetesimals of 100 to 1000 km in size into rocky Earth-mass planets is the main outcome of this theory. Beyond the → snow line in the disk, if the masses of these cores of rock and ice grow higher than 10 times that of Earth in less than a few million years, gas can rapidly accrete and give rise to giant gaseous planets similar to → Jupiter. If core building goes on too slowly, the disk gas dissipates before the formation of → giant planets can start. Finally the left-over planetesimals that could not agglomerate into rocky planets or core of giant planets remain as a → debris disk around the central object that has become a → main sequence star. An alternative to core accretion theory is formation of planets in a massive protoplanetary disk by → gravitational instabilities. The validity of these two theories is presently debated. See also → protoplanet.

protoplanet; → disk.

protoplanetary nebula
  پیش-میغ ِ سیاره‌ای   
piš-miq-e sayyâre-yi

Fr.: pré-nebuleuse planétaire   

preplanetary nebula.

proto-; → planetary; → nebula.

protoplasm
  پوروا-پلسم   
purvâplasm

Fr.: protoplasme   

The fluid substance within the living cell that consists of two major divisions, the cytoplasm and the nucleoplasm (cell nucleus). It is composed mainly of nucleic acids, proteins, lipids, carbohydrates, and inorganic salts.

proto- + -plasm, → plasma.

protosolar
  پوروا-خورشیدی   
purvâ-xoršidi

Fr.: protosolaire   

Describing the conditions prior to the formation of the → solar system, or pertaining to the → protostar that became the → Sun.

proto- + → solar.

protosolar abundance
  فراوانی ِ پوروا-خورشیدی   
farâvâni-ye purvâ-xoršidi

Fr.: abondance protosolaire   

The abundance of a chemical element pertaining to the proto-→ solar nebula from which the → solar system was formed. → CI chondrite; → CAI meteorite.

protosolar; → abundance.

protostar
  پوروا-ستاره   
purvâ-setâré

Fr.: protoétoile   

A stage in the process of → star formation, after the → gravitational collapse of the dense → pre-stellar core and before the initiation of → nuclear fusion in the central object which will eventually become a star. Protostars are classified into four groups: → Class 0, → Class I, → Class II, and → Class III.

proto- + → star.

protostellar
  پوروا-ستاره‌ای   
purvâ-setâreyi

Fr.: protostellaire   

Of or pertaining to → protostars.

proto-; → stellar.

protostellar collapse
  ر ُمبش ِ پوروا-ستاره‌ای   
rombeš-e purvâ-setâreyi

Fr.: effondrement protostellaire   

A → gravitational collapse leading to the formation of a → protostar.

protostellar; → collapse.

protostellar disk
  گرده‌ی ِ پوروا-ستاره‌ای   
gerde-ye purvâ-setâreyi

Fr.: disque protostellaire   

A disk of gas and dust surrounding a → protostar. These structures are rotating → accretion disks through which matter is transferred to protostars.

protostellar; → disk.

protostellar jet
  شان ِ پورواستاره‌ای   
šân-e purvâsetâre-yi

Fr.: jet protostellaire   

A high-velocity and highly → collimated jet associated with the earliest phase of → star formation that propagating along the polar axis of the → protostar-→ accretion disk system. Protostellar jets are usually detected in the [S II], [O I], and Hα lines and are therefore referred to as optical jets. They may have more than a parsec in length. Their formation is related to the → magnetohydrodynamics (MHD) of accretion disks. These jets are detected in protostellar sources over a wide range of masses, from the very early stages of formation (sources associated with infalling envelopes whose mass exceeds that of the growing star) all the way to the → classical T Tauri stars, whose envelopes have already dispersed. This phenomenon is thought to play a key role in regulating the star formation process by removing the excess → angular momentum of disk material and enabling matter to flow toward the center. Protostellar winds also provide an important → feedback mechanism between the forming star and the surrounding medium, to which they return mass and energy. Protostellar jets are at the origin of → bipolar outflows. The et sweeps up ambient → molecular cloud material into two thin shells, which manifest themselves as the observed bipolar lobes of → carbon monoxide (CO) emission. Once the molecular cloud material has been swept away (on a timescale of 105 years), the bipolar outflow disappears, leaving the protostellar jet to erratically fire away for a further 106-107 years.

protostellar; → jet.

protosun
  پوروا-خورشید   
purvâ-xoršid

Fr.: proto-Soleil   

The Sun at its protostellar formation stage, before becoming a main sequence star, nearly 5 billion years ago. The protosun was more luminous than today and larger, with a radius comparable to that of the orbits of the inner planets

proto- + → sun.

prototype
  پوروا-گون، پوروا-گونه   
purvâ-gun, purvâ-guné

Fr.: prototype   

The original or model on which something is based or formed.
Something that serves to illustrate the typical qualities of a class.

proto-; → type.

provable
  آوینیدنی   
âvinidani

Fr.: démontrable   

Capable of being demonstrated or proved.

prove; → -able.

prove
  آوینیدن   
âvinidan

Fr.: prouver   

To supply proof of, to establish or demonstrate the truth or validity of.

proof.

proverb
  فراواز   
farâvâz

Fr.: proverbe   

A short popular saying, usually of unknown and ancient origin, that expresses effectively some commonplace truth or useful thought (Dictionary.com).

pro-; → verb.

provocation
  فراوچ   
farâvac

Fr.: provocation   

1) The act of provoking.
2) Something that → incites, → instigates, angers, or irritates (Dictionary.com).

Verbal noun of → provoke.

provoke
  فراوچیدن   
farâvacidan

Fr.: provoquer   

1) To anger, enrage, exasperate, or vex.
2) To stir up, arouse, or call forth (feelings, desires, or activity).
3) To → incite or → stimulate (a person, animal, etc.) to action (Dictionary.com).

M.E., from O.Fr. provoker, provochier and directly from L. provocare "call forth, challenge," from → pro- "forth" + vocare "to call," → voice.

Farâvacidan, from farâ-, → pro-, + vacidan "to call," rarr; convoke.

prow
  فرال   
farâl

Fr.: proue   

The forepart of a ship or boat; bow; opposite to stern or poopPuppis.

From M.Fr. proue, from Upper It. (Genoese) prua, from L. prora "prow," from Gk. proira, related to pro "before, forward," → pro-.

Farâl, from farâ "forward" (farâ raftan "to go forward, proceed," farâ rândan "to drive forward"), equivalent to → pro-, + relation suffix -âl, → -al. Compare farâl with prow "bow," Fr. la proue "prow, bow," from dialectal It. proa, prua, from L. prora "bow," from Gk. proira, related to pro "before, forward."

Proxima b
  پروکسیما b   
Proksimâ b

Fr.: Proxima b   

An → extrasolar planet orbiting our nearest stellar neighbor → Proxima Centauri. The planet was detected through a long-term → radial velocity campaign and found to have an → orbital period of ~ 11.2 days, a → semi-major axis of ~ 0.05 → astronomical units (20 times closer to Proxima than the Earth is to the Sun), and a minimum mass 1.3 → Earth masses (M sin i = 1.3 M_Earth), i.e. ~ 30% larger than the Earth (Anglada-Escudé et al. 2016, Nature 536, 437). The planet's surface temperature should allow it to support liquid water, and its mass suggests that it might have a rocky surface. With a semi-major axis of ~ 0.05 AU, it lies in the center of the classical habitable zone for Proxima. However, Proxima Centauri is a → flare star and the → X-ray flux received by the planet is 400 times greater than the flux that Earth receives from the Sun. Energetic particles associated with the flares may erode the atmosphere or hinder the development of primitive forms of life. It is also not known whether the → exoplanet has a magnetic field, like Earth, which could shield it from the dangerous stellar radiation.

Proxima Centauri.

Proxima Centauri
  پروکسیما کنتاؤروس، نزدیکترین ~   
proksimâ Kentâwros, nazdiktarin ~

Fr.: Proxima du Centaure   

The closest star to the Sun, lying 4.24 → light-years away. Other designations: α Centauri C, GL 551, HIP 70890, or simply Proxima. It is the faintest of the three stars that make up the → Alpha Centauri system. Proxima Centauri is a → red dwarf of → spectral type M6 Ve. It has a magnitude of +11.0, but undergoes sudden brightness increases of up to 1 mag lasting several minutes. Proxima is a late-type → flare star with a rotation period of ~ 84 days. Its mass is about 0.123 → solar masses or 129 → Jupiter masses. Proxima orbits the binary system AB at a distance of about 15,000 → astronomical unit (AU)s, with a period of approximately 550,000 years (Kervella et al., 2016, arXiv:1611.0349). In about 200,000 years it will be at the same distance as AB and in 240,000 years it will be farther to Sun than AB. It has an → effective temperature of only around 3,050 K, a luminosity of 0.15 per cent of that of the Sun, a measured radius of 14 per cent of the radius of the Sun and a mass of about 12 per cent of the mass of the Sun. An → exoplanet, named → Proxima b, has been discovered orbiting our nearest neighbor star. Proxima experiences a seven-year activity cycle, similar to the Sun's 11-year cycle (B. J. Wargelin, B. J. et al., 2016, arXiv:1610.03447). But unlike the Sun's relatively moderate flares, Proxima's outbursts of X-ray and ultraviolet radiation could prove deadly for any hypothetical life on its planet, Proxima b.

Proxima, feminine of proximus "nearest," superlative of prope "near;" → approximate; → Centaurus.

Proksimâ, from L., as above; Kentâwros, → Centaurus; nazdiktarin, superlative of nazdik "near," from Mid.Pers. nazdik "near," from nazd "close" (Mid.Pers. nazd, nazdik "near," nazdist "first;" O.Pers. ašna- "close;" Av. nazdišta- "nearest, next," nazdyo "nearer to," nas- "to come near, approach, reach;" cf. Skt. nédīyas- "closer, very close," nas- "to approach, to reach") + -ik, → -ic.

<< < -es -iv -ti 21- A r abe abs abs acc acc acc act act ada adi adu aff age alc Alf ali all alp alt ama amp ana ang ang ann ano ant ant ape apo app aps arc Arg ari art ass ast ast ast atm ato att aur aut axi B r bac Bal Bar Bar Bay bec Ber Bet Bie bij bin bio bis bla bla blu blu bol Bor bou Bra bre bro Bug C-s cal Cam can car Car Cas cat cav cel cen cer Cha cha cha che cho cir cir cir 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 coo cor cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl dar dat daw de- Deb dec dec dee def deg del Den dep der det deu dew dic dif dif dil dip dir dis dis dis dis dis div dog Dop dou dra dua dus dwa dyn e-m ear ecl eco eff ein Ein elb ele ele ele ele Els emi emp ene enr env epi equ equ Eri est Euc eva evo exc exc exh exo exp exp ext ext f-n Fah fam fau fee Fer fib fil fin fir fix fle flu foc for for for fra fre fre fri fun fuz gal gal gal Gan gau GCN gen geo geo geo geo Gl glo gra gra gra gra gra gre gro GW1 hab hal han HAR haz hea hel hel Hen Her heu Hig Hil hol hop hor hou Hub Hum Hyd hyd hyd hyp hys ide ign ima imp imp inc inc ind ine inf inf inf inh INP ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jos Jun K2 Kep key kin Kol lag lam Lan lar las lav lea leg len lev lig lim lin lin lin lis lob loc log lor low lum lun lun Lym Mac mag mag mag mag mag mai Mal mar mas mas mat max mea mea mee Men mer met met met mic mid Mil min Mir mix mod mod mol mon Mor mou mul muo mys nan nat nav nec Nep neu New New NGC nob nom non non nor not nuc nuc num Nyq obj obs obs oce oen OH omn opa ope opt opt opt orb ord Ori ort osc out ove oxy pal pan par Par par par pas pea Pen per per per per per pet pha pho pho pho phy pie Pit Pla pla pla pla ple Poi pol pol pol pol pop pos pos pow pre pre pre Pre pri pri pri pro pro pro pro pro pro Pro pub pul pyr qua qua qua qua Qui rad rad rad rad rad rad ram ran rat rea rec rec rec red ref ref reg reg rel rel rem rep res res res ret rev rho Rie rim riv rol Ros rot rul S a Sah san Sat sca Sch Sch scr sec sec sec sei sel sem sep set sha she sho sid sig sil sim sin sit sky slu sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spl spr sta sta sta sta sta ste ste sti sto str str sub sub sub sug sun sup sup sup sup sur syl syn sys tal Tay tel ten ter tex the the the thi tho thu tid tim tod top tot tra tra tra tra tri tri tro tru tur twi Typ UFO ult unc uni uni uni upg ura uti val var vec vel ver ver vig vir vis voc von wak Was wav wax wea wei whi Wie win WN6 wom X-r yel you zer zod > >>