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 : far
gravitational acceleration
  شتاب ِ گرانشی   
šetâb-e gerâneši (#)

Fr.: accélération gravitationnelle   

The acceleration caused by the force of gravity. At the Earth's surface it is determined by the distance of the object form the center of the Earth: g = GM/R2, where G is the → gravitational constant, and M and R are the Earth's mass and radius respectively. It is approximately equal to 9.8 m s-2. The value varies slightly with latitude and elevation. Also known as the → acceleration of gravity.

gravitational; → acceleration.

gravitational attraction
  درکشش ِ گرانشی   
darkešeš-e gerâneši

Fr.: attraction gravitationnelle   

The force that pulls material bodies toward one another because of → gravitation.

gravitational; → attraction.

gravitational collapse
  رمبش ِ گرانشی   
rombeš-e gerâneši (#)

Fr.: effondrement gravitationnel   

Collapse of a mass of material as a result of the mutual → gravitational attraction of all its constituents.

gravitational; → collapse.

gravitational constant
  پایای ِ گرانشی   
pâyâ-ye gerâneši (#)

Fr.: constante gravitationnelle   

A fundamental constant that appears in → Newton's law of gravitation. It is the force of attraction between two bodies of unit mass separated by unit distance: G = 6.673 x 10-8 dyn cm2 g-2 or 6.673 x 10-8 cm3s-2g-1, or 6.673 x 10-11 N m2 kg-2 or 6.673 x 10-11 m3s-2kg-1. It was first measured in 1798 by Henry Cavendish (1731-1810), 71 years after Newton's death. Same as the → Newtonian constant of gravitation.

gravitational; → constant.

gravitational contraction
  ترنگش ِ گرانشی   
terengeš-e gerâneši

Fr.: contraction gravitationnelle   

Decrease in the volume of an astronomical object under the action of a dominant, central gravitational force.

gravitational; → contraction.

gravitational coupling constant
  پایای ِ جفسری ِ گرانشی   
pâyâ-ye jafsari-ye gerâneši

Fr.: constante de couplage gravitationnel   

The dimensionless gravitational constant defined as the gravitational attraction between pair of electrons and normally given by: αG = (Gme2) / (ħc) = (me / mP)2 ~ 1.7518 × 10-45, where ħ is → Planck's reduced constant, c the → speed of light, me is the → electron mass, and mP is the → Planck mass.

gravitational; → coupling; → constant.

gravitational encounter
  رویارویی ِ گرانشی   
ruyâruyi-ye gerâneši

Fr.: rencontre gravitationnelle   

An encounter in which two moving bodies alter each other's direction and velocity by mutual → gravitational attraction.

gravitational; → encounter.

gravitational energy
  کاروژ ِ گرانشی   
kâruž-e gerâneši

Fr.: énergie gravitationnelle   

Same as → gravitational potential energy.

gravitational; → energy.

gravitational equilibrium
  ترازمندی ِ گرانشی   
tarâzmandi-ye gerâneši (#)

Fr.: équilibre gravitationnel   

The condition in a celestial body when gravitational forces acting on each point are balanced by some outward pressure, such as radiation pressure or electron degeneracy pressure, so that no vertical motion results.

gravitational; → equilibrium.

gravitational field
  میدان ِ گرانشی   
meydân-e gerâneši (#)

Fr.: champ gravitationnel   

The region of space in which → gravitational attraction exists.

gravitational; → field.

gravitational force
  نیروی ِ گرانشی   
niru-ye gerâneši (#)

Fr.: force gravitationnelle   

The weakest of the four fundamental forces of nature. Described by → Newton's law of gravitation and subsequently by Einstein's → general relativity.

gravitational; → force.

gravitational instability
  ناپایداری ِ گرانشی   
nâpâydâri-ye gerâneši (#)

Fr.: instabilité gravitationnelle   

The process by which fluctuations in an infinite medium of size greater than a certain length scale (the Jeans length) grow by self-gravitation.

gravitational; → instability.

gravitational interaction
  اندرژیرش ِ گرانشی   
andaržireš-e gerâneši

Fr.: interaction gravitationnelle   

Mutual attraction between any two bodies that have mass.

gravitational; → interaction.

gravitational lens
  عدسی ِ گرانشی   
adasi-ye gerâneši (#)

Fr.: lentille gravitationnelle   

A concentration of matter, such as a galaxy or a cluster of galaxies, that bends light rays from a background object, resulting in production of multiple images. If the two objects and the Earth are perfectly aligned, the light from the distant object appears as a ring from Earth. This is called an Einstein Ring, since its existence was predicted by Einstein in his theory of general relativity.

gravitational; → lens.

gravitational lens equation
  هموگش ِ عدسی ِ گرانشی   
hamugeš-e adasi-ye gerâneši

Fr.: équation de lentille gravitationnelle   

The main equation of gravitational lens theory that sets a relation between the angular position of the point source and the observable position of its image.

gravitational; → lens; → equation.

gravitational lensing
  لنزش ِ گرانشی   
lenzeš-e gerâneši

Fr.: effet de lentille gravitationelle   

The act of producing or the state of a → gravitational lens.

gravitational; → lensing.

gravitational lensing time delay
  درنگ ِ زاییده‌ی ِ لنزش ِ گرانشی   
derang-e zâyide-ye lenzeš-e gerâneši

Fr.: retard dû à l'effet de lentille gravitationnelle   

The difference in light travel times along the various light paths from the source to the observer when the source image is divided into several images because of → gravitational lensing. According to the theory of → general relativity, light rays are deflected in the vicinity of massive objects. If the light source and the deflector are sufficiently well aligned with the observer, and obey some conditions on their distances (→ Einstein radius), we can observe several (generally distorted and magnified) images of the source. A property of → strong lensing is that the light travel time from the source to the observer is generally not identical for the different images. In other words, we not only see several images of one same object, but we also see this object, in each image, at different times. This means, in one image the lensed object will be observed before the other image. Given a physical model of the gravitational lens, the light travel time for each image can be computed. The expression giving the time delay has two components: a term is called → geometric delay, and the second term, known as the → Shapiro time delay. The latter is due to time dilation by the gravitational field of the lens, a direct consequence of general relativity. See also → time delay distance.

gravitational; → lensing; → time; → delay.

gravitational mass
  جرم ِ گرانشی   
jerm-e gerâneši (#)

Fr.: masse gravitationnelle   

The mass of an object measured using the effect of a gravitational field on the object.

gravitational; → mass.

gravitational potential energy
  کاروژ ِ توند ِ گرانشی   
kâruž-e tavand-e gerâneši

Fr.: énergie potentielle gravitationnelle   

1) The energy that an object possesses because of its position in a → gravitational field, especially an object near the surface of the Earth where the → gravitational acceleration can be assumed to be constant, at about 9.8 m s-2.
2) In a two body system. It is the amount of work done in bringing the mass m to the distance R from M: EP = -GMm/R, where G is the → gravitational constant.
3) For a uniform sphere. It is EP = -(3/5)GM2/R, where G is the gravitational constant and M is the mass contained in the sphere of radius R.

gravitational; → potential; → energy.

gravitational radiation
  تابش ِ گرانشی   
tâbeš-e gerâneši (#)

Fr.: rayonnement gravitationnel   

The → energy transported by → gravitational waves. Gravitational radiation is to → gravity what light is to → electromagnetism.

gravitational; → radiation.

<< < -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 > >>