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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 13176 Search : in
ring opening angle
  زاویه‌ی ِ گشایش ِ حلقه   
zâviye-ye gošâyeš-e halqé

Fr.: angle d'ouverture des anneaux   

Of → Saturn, the angle between the line of sight and the ring plane. Also known as elevation angle, tilt angle.

ring; → open; → angle.

Zâviyé, → angle; gošâyeš "opening," verbal noun from gošudan, gošâdan "to open up, loose, let free;" gošâd "opened; ample, broad;" Mid.Pers. wišâdan "to let free;" Khotanese hīyā "bound;" O.Pers. višta "untied, loosened," vištāspa- "with loosened horses" (personal name); Av. višta "untied," ā-hišāiiā "holds fettered," hita- "fastened, tied on, put to;" cf. Skt. sā- "to bind, fasten, fetter," sitá- "bound," ví-sita- "untied;" halqé, → ring.

ring system
  راژمان ِ حلقه‌ای   
râžmân-e halqe-yi

Fr.: système d'anneaux   

planetary ring system.

ring; → system.

ringdown
     

Fr.: desexcitation finale   

The last stage of → merger between two → black holes undergoing → inspiral. At the end of the evolution of a → binary black hole system, the black holes get close enough to → merge together into a single, larger black hole (→ black hole merger). The resulting black hole is at first distorted and asymmetric, but in the ringdown process the black hole's vibrations decay due to → gravitational radiation leaving finally a quiescent, spinning black hole.

M.E. ring, from O.E. hringan; akin to O.Norse hringja "to ring;" → down.

ringlet
  حلقک   
halqak

Fr.: annelet   

1) A small ring.
2) Any of the thin or narrow rings that compose the major → Saturn's rings.

ring; → -let.

ripple
  چیناو   
cinâv

Fr.: ondulation, ride   

A wave on a fluid surface, of sufficiently short wavelength, in which gravity is the dominant influence.

Of unknown origin, perhaps frequentative of rip (v.) "to tear apart."

Cinâv, literally "water wrinkle," from cin "fold, plait, wrinkle" + âv, variant of âb, → water.

rise
  ۱) بر‌آمدن؛ ۲) بر‌آمد   
1) barâmadan (#); 2) barâmad (#)

Fr.: 1) se lever; 2) lever   

1) Of a heavenly body, to ascend above the horizon. → set.
2) An act or instance of rising; appearance above the horizon. → moonrise, → sunrise

M.E. risen (v.); O.E. risan; cf. O.N. risa, Goth. urreisan "to rise," O.H.G. risan "to rise, flow," Ger. reisen "to travel."

Barâmadan, from bar- "up; upon; on; in; into; at; forth; with; near; before; according to" (Mid.Pers. abar; O.Pers. upariy "above; over, upon, according to;" Av. upairi "above, over," upairi.zəma- "located above the earth;" cf. Gk. hyper- "over, above;" L. super-; O.H.G. ubir "over;" PIE base *uper "over") + âmadan "to come, to occur, to become" (Mid.Pers. âmatan; O.Pers. gam- "to come; to go," Av. gam- "to come; to go," jamaiti "goes;" Proto-Iranian *āgmatani; Skt. gamati "goes;" Gk. bainein "to go, walk, step;" L. venire "to come;" Tocharian A käm- "to come;" O.H.G. queman "to come;" E. come; PIE root *gwem- "to go, come").

rising
  بر‌آمد، بر‌آیش   
barâmad (#), barâyeš (#)

Fr.: lever   

The act of rising; the appearance of a celestial body above the horizon. Opposite of → setting.

Verbal noun of → rise.

risk
  ریسک   
risk (#)

Fr.: risque   

Exposure to the chance of injury or loss; a hazard or dangerous chance (Dictionary.com).

From Fr. risque, from It. risco, riscio (modern rischio), from riscare "to run into danger," of uncertain origin.

Risk, loan from Fr.

Ritchey-Chretien telescope
  تلسکوپ ِ ریچی-کرتین، دوربین ِ ~   
teleskop-e Ritchey-Chrétien, durbin-e ~

Fr.: télescope Ritchey-Chrétien   

A type of → Cassegrain telescope in which the → primary mirror is a → hyperboloid. It is designed to eliminate → coma and → spherical aberration, thus providing a relatively large field of view as compared to a more conventional configuration.

Named after the American astronomer George Ritchey (1864-1945) and the French optician Henri Chrétien (1879-1956); → telescope.

Ritz combination principle
  پروز ِ میازش ِ ریتز   
parvaz-e miyâzeš-e Ritz

Fr.: principe de combinaison de Ritz   

An empirical rule discovered before the advent of quantum mechanics which states that it is possible to find pairs of spectral lines, which have the property that the sum of their wavenumbers is also an observed spectral line.

Named after Walther Ritz (1878-1909), a Swiss theoretical physicist; → combination; → principle.

rival
  هماورد   
hamâvard (#)

Fr.: rival   

1) A person who is competing for the same object or goal as another, or who tries to equal or outdo another; competitor.
2) A person or thing that is in a position to dispute another's preeminence or superiority (Dictionary.com).

From L. rivalis "a rival, adversary; neighbor," originally, "one who uses a stream in common with another," from riv(us) "stream, brook," + -alis, → -al.

Hamâvard "a rival; an adversary in a combat," from ham- "together," → com-, + âvard "battle, struggle," variants nabard, nibard, nâvard "fight, struggle, war," ultimately from Proto-Ir. *part- "to fight, to struggle."

rivalry
  هماوردی   
hamâvardi (#)

Fr.: rivalité   

1) The action, position, or relation of a rival or rivals; competition.
2) An instance of this (Dictionary.com).

Noun from → rival.

river
  رود   
rud (#)

Fr.: rivière   

A large natural stream of water flowing in a definite course.

M.E., from O.Fr. rivere, riviere, from V.L. *riparia "riverbank, seashore, river," noun use of feminine of L. riparius "of a riverbank."

Rud, from Mid.Pers. rôd "river," O.Pers. rautah- "river;" cf. Skt. srotas- "river," sru- "to flow;" Pali sota- "stream, flood;" Gk. rhoos "a stream, a flowing," from rhein "to flow;" O.E. stream; Ger. Strom; PIE base *sreu- "to flow."

roAp star
  ستاره‌ی Apی ِ تند نونده   
setâre-ye Ap-ye tond navandé

Fr.: étoile Ap à oscillation rapide   

Same as → rapidly oscillating Ap star

rapidly oscillating Ap star

Robertson-Walker metric
  متریک ِ روبرتسون-واکر   
metrik-e Robertson-Walker (#)

Fr.: métrique de Robertson-Walker   

The mathematical description of the interval (→ space-time separation) between → events ("points" in space-time) in a → homogeneous and → isotropic → Universe. It results from an exact solution of → Einstein's field equations of → general relativity. Under the assumptions, the Robertson-Walker interval is expressed by:
ds2 = c2dt2 - R2(t) [dr2/(1 - kr2) + r22 + r2sin2θ dθ2)].
Same as Friedmann-Lemaître-Robertson-Walker metric. Compare → Minkowski metric.

Named after Howard Percy Robertson (1903-1961), American mathematician and physicist, and Arthur Geoffrey Walker (1909-2001), British mathematician and physicist, for their contributions to physics and physical cosmology; → metric.

robot
  روبوت   
robot (#)

Fr.: robot   

A machine that does mechanical, routine tasks on command.

From Czech, coined by Karel Čapek in the play R.U.R. (1920), from the base robot-, as in robota "compulsory labor," robotník "peasant owing such labor," from robotiti "to work, drudge."

Robot, loan from E., as above.

robust
  تناور   
tanâvar (#)

Fr.: robuste   

The quality of a model when it is insensitive to small discrepancies in assumptions.

From L. robustus "strong and hardy," literally "as strong as oak," from robur, robus "hard timber, strength," also "a special kind of oak," named for its reddish heartwood, from L. ruber, → red.

Tanâvar "robust, stout, corpulent," from tan "corpus, body," → if and only if + âvar contraction of âvarandé agent noun of âvardan "to bring; to cause, produce," → collect.

Roche limit
  حد ِ رُش   
hadd-e Roche

Fr.: rayon de Roche   

The smallest distance at which a → satellite under the influence of its own → gravitation and that of a central mass about which it is describing a → Keplerian orbit can be in equilibrium. This does not, however, apply to a body held together by the stronger forces between atoms and molecules. At a lesser distance the → tidal forces of the → primary body would break up the → secondary body. The Roche limit is given by the formula d = 1.26 RMMm)1/3, where RM is the radius of the → primary body, ρM is the → density of the primary, and ρm is the density of the secondary body. This formula can also be expressed as: d = 1.26 Rm (MM/Mm)1/3, where Rm is the radius of the secondary. As an example, for the Earth-Moon system, where RM = 6,378 km, ρM = 5.5 g cm-3, and ρm = 2.5 g cm-3 is 1.68 Earth radii.

Named after Edouard Albert Roche (1820-1883), the French astronomer who first calculated this theoretical limit in 1848; → limit.

Roche lobe
  لپ ِ رُش   
lap-e Roche

Fr.: lobe de Roche   

The region around a star in a → binary system within which orbiting material is gravitationally bound to that star. The point at which the Roche lobes of the two stars touch is called the → inner Lagrangian point. → equipotential surface.

Roche limit; → lobe.

Roche lobe overflow (RLOF)
  سرریز ِ لپ ِ رُش   
sarriz-e lap-e Roche

Fr.: débordement du lobe de Roche   

A process in a → binary system when a star fills its → Roche lobe, often by becoming a → giant or → supergiant during the later stages of → stellar evolution. When the star expands, any material that passes beyond the Roche lobe will flow onto the binary → companion, often by way of an → accretion disk. This occurs through the → inner Lagrangian point where the gravity of the two stars cancels. The RLOF is responsible for a number of phenomena including → cataclysmic variables, → Type Ia supernovae, and many → X-ray binary systems.

Roche lobe; → overflow.

<< < -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 > >>