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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Number of Results: 221 Search : era
absolute acceleration
  شتاب ِ اوست   
šetâb-e avast

Fr.: accélération absolue   

For a body that moves with respect to a rotating → reference frame, the vector sum of the observed acceleration, the → Coriolis acceleration, and the → centrifugal acceleration. See also the → Coriolis theorem.

absolute; → acceleration.

absolute temperature
  دما‌ی ا َوَست   
damâ-ye avast

Fr.: température absolue   

The value of a → temperature in the → Kelvin scale. The absolute temperature is equal to the temperature on the → Celsius scale -273.16 °C.

absolute; → temperature.

accelerate
  شتابیدن، شتافتن؛ شتاباندن   
šetâbidan (#), šetâftan (#); šetâbândan (#)

Fr.: accélérer   

(v.tr.) To increase the velocity of a body; to cause to undergo acceleration.
(v.intr.) To increase in speed.

Verbal form of → acceleration.

accelerated motion
  جنبش ِ شتابدار   
jonbeš-e šetâbdâr (#)

Fr.: mouvement accéléré   

The motion of an object subject to → acceleration. Opposite to → uniform motion.

Accelerated, from → accelerate; → motion.

Jonbeš, → motion; šetâbdâr "accelerated," from šetâbaccelerate + dâr "having, possessor" (from dâštan "to have, to possess," Mid.Pers. dâštan, O.Pers./Av. root dar- "to hold, keep back, maitain, keep in mind;" cf. Skt. dhr-, dharma- "law;" Gk. thronos "elevated seat, throne;" L. firmus "firm, stable;" Lith. daryti "to make;" PIE *dher- "to hold, support").

accelerating
  شتابنده   
šetâbandé (#)

Fr.: en accélération   

Moving or proceeding with → acceleration; e.g. → accelerating system; → accelerating Universe.

Verbal adj. from → accelerate.

accelerating expansion of the Universe
  گسترش ِ شتابنده‌ی ِ گیتی   
gostareš-e šetâbande-ye giti

Fr.: expansion accélérée de l'Univers   

accelerating Universe.

accelerating; → expansion; → Universe.

accelerating system
  راژمان ِ شتابنده   
râžmân-e šetâbandé

Fr.: système en accélération   

A material system that is subject to a constant force in each and every one of its instantaneous points of trajectory.

accelerating; → system.

accelerating Universe
  گیتی ِ شتابنده   
giti-ye šetâbandé (#)

Fr.: univers en accélération   

The deduction based on the observation that the most distant → Type Ia supernovae are fainter than that expected from their → redshifts in a matter-only dominated expanding Universe. The faintness is attributed to larger distances resulting from an accelerating Universe driven by presence of a new component with strongly negative pressure. This component that makes the Universe accelerate is named → dark energy. The deceleration or acceleration of an expanding Universe, given by the general relativistic equation, is: R../R = -(4/3)πGρ(1 + 3w), where R is the linear → cosmic scale factor of the expanding Universe, G the → gravitational constant, ρ the mean density of the Universe, and w the → equation of state parameter representing dark energy. The expansion accelerates whenever w is more negative than -1/3. The Nobel Prize in Physics 2011 was awarded to the initiators of this concept, Saul Perlmutter, Brian P. Schmidt, and Adam G. Riess, for their discovery of the accelerating expansion of the Universe through observations of distant supernovae. See also the original paper: Perlmutter et al. 1999, ApJ 517, 565.

accelerating; → universe.

acceleration
  شتاب   
šetâb (#)

Fr.: accélération   

The rate at which the velocity of an object changes with time.

Acceleration, from accelerate, from L. accelerare "quicken," from → ad- "to" + celerare "hasten," from celer "swift" (cf. Skt. car, carati "to move, go, drive," Gk. keles "fast horse, horse race," Av. kar- "to walk, move, go around," Mod.Pers. cal, calidan "to move, to go, to walk" (jald? "quick, active, brisk"), Gilaki/Hamadâni jal "quick, fast,"Lori žil "motion, impulse"); PIE *kel- "to drive, set in swift motion."

Šetâb "quickness, haste, speed," Mid.Pers. ôštâp "hurry, haste," ôštâftan "to hurry, hasten," from *abi.stap-, from abi- " to; in addition to; against" + *stap- "to oppress," Arm. (loanword) štap "haste, trouble."

acceleration of gravity
  شتاب ِ گرانی   
šetâb-e gerâni

Fr.: accélération de la gravité   

The acceleration that an object experiences because of gravity when it falls freely close to the surface of a massive body, such as a planet. Same as → gravitational acceleration.

acceleration; → gravity.

acceleration parameter
  پارامون ِ شتاب   
pârâmun-e šetâb

Fr.: paramètre d'accéleration   

A measure of the departure from a constant rate of the acceleration of the Universe, expressed by: q(t) = R(t)R ..(t)/R .2(t), where R(t) represents the size of the Universe at time t. Traditionally, a negative sign is inserted in the above equation for the → deceleration parameter.

acceleration; → parameter.

accelerator
  شتابگر   
šetâbgar (#)

Fr.: accélérateur   

A machine which accelerates charged atomic (ions of various elements) or subatomic particles (usually electrons and protons) to high energies. → cyclotron; → synchrotron.

Accelerator, from accelerate, → acceleration, + -or agent suffix, from M.E. -or, -our, from O.F. -eor, -eur, from L. -or.

Šetâbgar, from šetâbacceleration + -gar agent suffix, → -or.

adiabatic temperature gradient
  زینه‌ی ِ دمای ِ بی‌دررو   
zine-ye damâ-ye bidarrow

Fr.: gradient de température adiabatique   

The temperature gradient defining the → radiative equilibrium condition in a region. It is expressed as: dT/dr = (1 - 1/ γ)((T / P)(dP / dr), where T and P are temperature and pressure, dT / dr and dP / dr temperature and pressure gradients respectively, and γ = CP / CV. For radiative equilibrium to be stable against → convection, the actual temperature gradient must be less than the adiabatic temperature gradient, i.e. |dT /dr|rad < |dT /dr|ad. See also → Schwarzschild's criterion.

adiabatic; → temperature; → gradient.

agglomerate
  ۱) برگلمیدن؛ ۲) برگلمیده؛ ۳) برگلم   
1) bargolemidan; 2) bargolemidé; 3) bargolem

Fr.: 1) agglomérer; 2,3) aggloméré   

1) (v.) To collect or gather into a cluster or mass.
2) (adj.) Gathered together into a cluster or mass.
3a) (n.) A mass of things clustered together.
3b) A rock composed of rounded or angular volcanic fragments (Dictionary.com).

From L. agglomeratus, p.p. of agglomerare "to wind or add onto a ball," from → ad- "to" + glomerare to "wind up in a ball," from glomus (genitive glomeris) "ball of yarn," globus "globe;" PIE *gel- "to make into a ball."

Bargolemidan, from suffix bar- "to, on, upon," + golem, from Lori, Laki golemâ, golama "curd, obtained from milk by coagulation, used to make cheese," Lori golem "stagnating water," Sangesari, Semnâni, Sorxe-yi, Lâsgardi golma, "boll, i.e. the rounded seed capsule of plants such as cotton," + -idan infinitive suffix.

agglomeration
  برگلمش   
bargolemeš

Fr.: agglomération   

1) A jumbled cluster or mass of varied parts.
2) The act or process of agglomerating (Dictionary.com).

Verbal noun of → agglomerate.

Alderamin (α Cephei)
  ذراع ِ یمین   
Zerâ'-e Yamin

Fr.: Alderamin   

The brightest star in → Cepheus and a → subgiant star of apparent visual magnitude 2.44. Its → spectral type is A7 and distance 49 → light-years.

Alderamin, from Ar. al dhirâ' al-yamin "right arm" (of Cepheus), from Ar. dhirâ' "arm" + yamin "right".

Zerâ'-e Yamin, from Ar. al dhira al-yamin.

Alpheratz (α Andromedae)
  رأس‌المسلسله   
Ra's-ol-Mosalsalé

Fr.: Alphératz   

The brightest star in → Andromeda with a visual magnitude of 2.07. Alpheratz is a blue → subgiant star of spectral type B8 IV lying at a distance of about 97 → light-years. It is particularly remarkable because of the unusual strength of mercury and manganese absorption lines in its spectrum.

Other names for this star are Alpherat, Sirrah, or Sirah. These names derive from Ar. As-Surrat al-Faras (السره‌الفرس) "The Horse's Navel," from surrat (سره) "navel" + faras (فرس) "horse". The name refers to the location of the star in the figure of → Pegasus. However, the star is now considered to belong to the constellation → Andromeda.

Ra's-ol-Mosalsalé, from Ar. Ar-Ra's al-Mar'ah al-Musalsalah "The head of the chained woman," from Ra's "head" + Mar'ah "woman" + Musalsalah "chained".

alteration
  دگرگونی، دگرگونش   
degarguni, degarguneš

Fr.: altération   

1) The act or process of altering; the state of being altered.
2) The result of altering.

Verbal noun of → alter.

Amazonian era
  دوران ِ آمازونی   
dowrân-e Âmâzoni

Fr.: ère amazonienne   

The current geologic era on Mars that began around 2 billion to 3 billion years ago. It is characterized by lower geologic activity such as volcanism and only occasional releases of underground water. A dry environment with a very thin atmosphere in which water can only exist as a solid or a gas, not as a liquid. → Noachian era; → Hesperian era.

Named for the young lava-covered plains called Amazonia Planitia. → era.

angular acceleration
  شتاب ِ زاویه‌ای   
šetâb-e zâviye-yi (#)

Fr.: accélération angulaire   

The rate of change of → angular velocity: α = ω(dω/dθ), where ω is the angular velocity and θ the rotation angle with respect to the reference axis.

angular; → acceleration.

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