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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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primary mirror
  آینه‌ی ِ نخستان   
âyene-ye noxostân

Fr.: miroir primaire   

In a → reflecting telescope, the first mirror that collects the light and focuses it to the → focal plane.

primary; → mirror.

primary rainbow
  رنگین‌کمان ِ نخستان   
rangin-kamân-e naxostân

Fr.: arc-en-ciel primaire   

The main rainbow that forms between about 40° and 42° from the → antisolar point (or about 50° from the → antisolar point), as viewed by the observer. The light path involves → refraction and a → single  → reflection inside the water → droplet. If the drops are large, 1 millimeter or more in diameter, red, green, and violet are bright but there is little blue.

As the droplets get smaller, red weakens.

Rainbows are not seen in midday since the whole 42° circle is below the horizon at most latitudes. So rainbows tend to be seen most in the later afternoon when a thundershower has passed and the Sun is illuminating from the west.

primary; → rainbow.

primary star
  ستاره‌ی ِ نخستان   
setâre-ye naxostân

Fr.: étoile principale   

In a → multiple star system, the most massive → component. In other words, the star nearest to the system's → center of garvity.

primary; → star .

prime
  نخست، نخستین، نخستی   
naxost, naxostin, naxosti

Fr.: premier   

1) Of the first importance; of the highest rank.
2) Same as → prime number.

M.E., from L. primarius "of the first rank, principal," from primus "first."

Naxost, naxostin, naxosti, from Mid.Pers. naxust "the first," Parthian Mid.Pers. nxwšt, from naxu, Manichean Parthian nwx "beginning" + -ist superlative suffix, Av. -išta-, cf. Skt. -istha-, Gk. -istos, O.H.G. -isto, -osto, O.E. -st, -est, -ost.

prime focus
  کانون ِ نخستی   
kânun-e naxosti

Fr.: foyer primaire   

The focal point of a large primary reflecting mirror. This focus actually falls at a point just within the upper structure of the telescope and provides a large field of view.

primary; → focus.

prime meridian
  نیمروزان ِ نخستی   
nimruzân-e noxosti

Fr.: méridien origine   

The meridian at which longitude is defined to be 0°. The meridian running through Greenwich.

primary; → meridian.

prime number
  عدد ِ نخست   
'adad-e naxost

Fr.: nombre premier   

A number which is divisible by no whole number other than itself and one.

prime; → number.

prime vertical
  هجین ِ نخستی   
hajin-e noxosti

Fr.: premier vertical   

The great circle through the observer's zenith that intersects the horizon at the west and east points. → vertical circle.

primary; → vertical.

primeval atom
  اتم ِ نخستین   
atom-e naxostin

Fr.: atome primitif   

Lemaître's (1931) name for the early dense Universe, which later became known as the → Big Bang theory.

From L. primaevus "early in life," from primus "first," → prime, + aevum "an age," + → -al; → atom.

primordial
  بن‌آغازین   
bonâqâzin

Fr.: primordial   

Pertaining to or existing at or from the very beginning.

From L.L. primordialis "first of all, original," from L. primordium "the beginning," from primus "first" + stem of ordiri "to begin."

Bonâqâzin, from bon "basis; root; foundation; bottom" (Mid.Pers. bun "root; foundation; beginning," Av. būna- "base, depth," cf. Skt. bundha-, budhná- "base, bottom," Pali bunda- "root of tree") + âqâzin "pertaining to the beginning," from âqâz "beginning" (Proto-Iranian *āgāza-, from prefix ā- + *gāz- "to take, receive," cf. Sogdian āγāz "beginning, start," pcγz "reception, taking").

primordial abundance
  فراوانی ِ بن‌آغازین   
farâvâni-ye bonâqâzin

Fr.: abondance primordiale   

The relative amount of a light element (e.g. deuterium, lithium, helium) synthesized in the early Universe.

primordial; → abundance.

primordial black hole
  سیه‌چال ِ بن‌آغازین   
siyahcâl-e bonâqâzin

Fr.: trou noir primordial   

A black hole formed following the Big Bang event due to incredibly violent turbulence that squeezed concentrations of matter to high densities. These black holes, first suggested by Stephen Hawking, are expected to have a mass comparable to that of a mountain and a size as small as an atom. Same as → mini black hole.

primordial; → black hole.

primordial curvature perturbation
  پرتورش ِ خمیدگی ِ بن‌آغازین   
partureš-e xamidegi-ye bonâqâzin

Fr.: perturbation de courbure primordiale   

In cosmological models, the phenomenon that is supposed to seed the → cosmic microwave background anisotropies and the structure formation of the Universe.

primordial; → curvature; → perturbation.

primordial galaxy
  کهکشان ِ بن‌آغازین   
kahkešân-e bonâqâzin

Fr.: galaxie primordiale   

A high redshift, metal-deficient galaxy that formed very early in the history of the Universe.

primordial; → galaxy.

primordial helium
  هلیوم ِ بن‌آغازین   
heliom-e bonâqâzin

Fr.: hélium primordial   

The helium element created in the → early Universe, around 3 minutes after the → Big Bang, when the temperature dropped to 109 degrees; in contrast to the helium being synthesized in stars. Based on observations of helium → emission lines in → H II regions of metal-poor dwarf galaxies (→ metal-deficient galaxy), the primordial 4He → chemical abundance (by mass) is estimated to be YP = 0.24672 ± 0.00017. Moreover, using observations of a near-pristine → intergalactic cloud, a value of 0.250 +0.033-0.025 has been reached (Cooke & Fumagalli, 2018, Nature Astronomy, 2, 657). The theoretical He abundance predicted by → Big Bang nucleosynthesis is 0.24709 ± 0.00017 (Pitrou et al., 2018, arXiv:1801.08023).

primordial; → helium.

primordial nucleosynthesis
  هسته‌هندایش ِ بن‌آغازین   
haste-handâyeš-e bonâqâzin

Fr.: nucléosynthèse primordiale   

The formation of → chemical elements in the → early Universe, between about 0.01 seconds and 3 minutes after the → Big Bang, when the nuclei of primordial matter collided and fused with one another. Most of the → helium in the → Universe was created by this process. Same as → Big Bang nucleosynthesis

primordial; → nucleosynthesis.

principal
  فرین   
farin

Fr.: principal   

First or highest in rank, importance, value, etc. See also → main.

M.E., from O.Fr. principal, from L. principalis "first in importance," from princeps "first, chief, prince," literally "that takes first," from primus "first" + root of capere "to take."

Farin literally "foremost," from far-, Mid.Pers. fra-; O.Pers. fra- "forward, forth;" Av. frā "forth," pouruua- "first;" cf. Skt. pūrva- "first," pra- "before, formerly;" Gk. pro; L. pro; O.E. fyrst "foremost," superlative of fore, E. fore + -in superlative suffix.

principal axis
  آسه‌یِ فرین   
âse-ye farin (#)

Fr.: axe principal   

1) Optics: Any imaginary line passing through the center of curvature of a → spherical mirror or → lens and the corresponding geometrical center. Principal axis is perpendicular to the mirror or lens at the pole. Rays of light parallel to the principal axis of a → concave mirror will appear to converge on a point in front of the mirror somewhere between the mirror's pole and its center of curvature. Same as → optical axis.
2) Mechanics: One of three mutually perpendicular axes of an object about which the → moment of inertia is maximum or minimum. More specifically, an object has an infinite number of moments of inertia. If an object is not symmetrical about all planes through its → center of mass, then there will be one → axis of rotation about which the moment of inertia is largest, and there will be one axis of rotation about which the moment of inertia is smallest. These two axes will always be perpendicular to each other and are the principal axes of the object. The third principal axis of an object is the axis perpendicular to these two axes. In general the → angular momentum (L) of a body spinning about a point O is not in the same direction as the axis of rotation, or that of the → angular velocity angular velocity (ω); that is L is not parallel to ω. For certain bodies, however, there can be certain axes for which L and ω are parallel. In that case L = , where I is the moment of inertia about the axis in question. In a symmetric rigid body, the axes of symmetry coincide with the principal axes of the moment of inertia

principal; → axis.

principal quantum number
  عدد ِ کو‌آنتومی ِ فرین   
adad-e kuântomi-ye farin

Fr.: nombre quantique principal   

In atomic physics, the first of a set of quantum numbers which describe an atomic orbital. Symbolized as n, it characterizes the size and energy of an orbital.

principal; → quantum; → number.

principle
  پَروَز   
parvaz (#)

Fr.: principe   

A fundamental, primary assumption, or general law from which others are derived.

From M.E., from O.Fr. principe, from L. principium "a beginning, first part," from princeps "first, chief, prince," literally "that takes first," from primus "first" + root of capere "to take."

Parvaz "origin, root, stock" (as used in particular by Ferdowsi); cf. Av. fra-vāza- "drawing from; leading onward," from Av. fra-, frā- "before; forward, forth" (fratəma- "first, front," pouruua- "first," fra-cara- "preceding;" O.Pers. fra- "forward, forth;" Mid.Pers. fra-; cf. Skt. pra- "before, formerly," prathama- "earliest, initial," pūrva- "first;" Gk. pro; L. pro; O.E. fyrst "foremost," superlative of fore) + vaz- "to draw, guide; bring; possess; fly; float," vazaiti "guides, leads" (cf. Skt. vah- "to carry, drive, convey," vahati "carries," pravaha- "bearing along, carrying," pravāha- "running water, stream, river;" L. vehere "to carry;" O.E. wegan "to carry;" O.N. vegr; O.H.G. weg "way," wegan "to move," wagan "cart;" M.Du. wagen "wagon;" PIE base *wegh- "to drive;" see also → flight).

<< < -es -it -sc 201 951 abe abs abs aca acc acc aco act ada adh ado aer aft air Alf alg alk alp Alt alt amb ana And ang ani ann ant ant ant apo app app Apu arc arg Arn art ass ast ast ast atm ato att aur aut avo azi bac bal bar bar bat Bea Bel bet bia big bin bio Bir bla bla blo Blu bol Boo bou box bre Bri bro bur cal cal Can cap car Car cat cau cel cen cen cha Cha cha che Chi chr cir cir civ cla clo clo CMB 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 coo cor cor cor Cos cos cos cou cou cra cri cro cry cul cur cyc D l dar dat day dea dec dec dec def def deg Del Den dep der det deu dew dic dif dif dil dip dir dis dis dis dis dis diu dog Dop dou Dra Dsc dus dwa dyn Dys Ear ecc eco edg egg Ein Ela ele ele ele ele ell eme emp enc eng ent epi equ equ equ eru eth Eur eve exa exc exe exi exo exp ext ext ext fab fai Fan fea fem fer fie fil fir fir fla fli flu foc for for for fra fre fre fri fun fuz gal gal gal Gam gau Gau gen geo geo geo geo Gib glo gov gra gra gra gra gre gro Gui H-a hal Ham har Hay hea hei hel Hel her het hie hig hoa hom hor hot Hub Hug hur hyd hyd hyl 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 inv ion iro Isl iso iso Jab jet Jov Jup Kar Kep kil Kip Kra Lag Lam Lan Lar las law lea Leg Leo lev lig lim lin lin lin lit loc loc log Lor low lum lun lun Lym Mac mag mag mag mag mag mai Mal map mas mas mat Mau mea mea med Men mer Mes Met met mic mic Mie mil min Mir mix mod mol mom Moo mor mov mul mur n-b nan nat nea neg Ner neu new New NGC noc nom non non nor nor nuc nuc nul nut obj obl obs occ oct off old one ope opp opt opt orb ord org Ori osc oth ove Owl P-s Pal par par par par Pas pat pec pen per per per per per Pha pha pho pho pho phy pie pix Pla pla pla pla Pli Poi pol pol pol pol por pos pos pow pre pre pre pre pri pri pri pro pro pro pro pro pro pro pub pul pyc qua qua qua qua qui rad rad rad rad rad rad rai 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 rur S5- Sal sat sca sca Sch sci Scu sec sec sed sel sel sem seq set sha she sho sid sie sil sim sin sit sky slo sno sod sol sol sol sol son sou spa spa spe spe spe spe sph spi spo squ sta sta sta sta ste ste ste Sti sto str str sub sub sub sul sup sup sup sup sur sur syl syn sys tal Tay tel ten ter tex the the the the Tho thr tid tim Tit too Tor tra tra Tra tra Tra tri Tri tru tub tur two Typ ult ult unc uni uni uni upl 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 > >>