An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



Number of Results: 20 Search : weak

Fr.: électrofaible   

Of, relating to, or being the → unification of → electromagnetism and the → weak interaction.

electro-; → weak.

electroweak epoch
  زیمه‌ی ِ برقانزار   
zime-ye barqânezâr

Fr.: époque électrofaible   

A period in the early history of the Universe lasting from 10-36 to 10-12 seconds after the → Big Bang. The electroweak epoch begins at the same time as cosmic → inflation is triggered. This is also the time when the → strong force breaks from the → grand unified force and ends with another → phase transition will occur in which the → weak interaction breaks from the → electroweak force.

electroweak; → epoch.

electroweak force
  نیروی ِ برقا نزار، ~ برقا کمزور   
niru-ye barqânezâr, ~ barqâkamzur

Fr.: force électrofaible   

The force that takes part in an → electroweak interaction.

electroweak; → force.

electroweak interaction
  اندرژیرش ِ برقانزار   
andaržireš-e barqânezâr

Fr.: interaction électrofaible   

The unified description of two of the four fundamental interactions of nature, → electromagnetism and the → weak interaction which would merge into a single force under conditions of extreme temperature (above 1016 degrees, 102 GeV) prevalent in the early history of the → Universe.

electroweak; → interaction.

electroweak star
  ستاره‌ی ِ برقانزار   
setâre-ye barqânezâr

Fr.: étoile électrofaible   

A postulated type of star that could form toward the end of a → massive star's life, after → nuclear fusion has stopped in its → core, and before the star → collapses into a → black hole. In those → extreme conditions, when → temperature and → density inside the star are very high, → quarks could convert into → leptons. Hence huge amounts of energy can be released, much of which would be in the form of → neutrinos.

electroweak; → star.

He-weak star
  ستاره‌ی ِ هلیوم-نزار   
setâre-ye heliom-nazâr

Fr.: étoile faible en hélium   

A → chemically peculiar star with very weak helium lines. Examples include 3 Sco, HD 176582, HD 217833, HR 2949, and HD 21699. The He-weak stars do not form a homogeneous group. Some of them display intense Si, or Ti and Sr lines, and are considered a hot extension of the magnetic → Ap/Bp stars. Others show overabundances of P and Ga, typically noted for → HgMn stars. The star HD 139160 belongs to the non-magnetic subgroup of He-weak stars.

helium; → weak; → line.

  نزار، تام، سست، کمنور، کمزور   
nezâr (#), tâm, sost (#), kamnur (#), kamzur (#)

Fr.: faible   

Not powerful or intense.
electroweak epoch, → electroweak force, → electroweak interaction, → weak anthropic principle, → weak arm spiral galaxy, → weak emission-line central star, → weak encounter, → weak equivalence principle, → weak force, → weak gravitational lensing, → weak interaction, → weak lensing, → weak nuclear force, → weak wind problem, → weak-line T Tauri star, → weak-wind O-type star.

From O.N. veikr "weak," cognate with O.E. wac "weak, pliant, soft," from P.Gmc. *waikwaz "yield," *wikanan "bend" (cf. Du. week "weak, soft, tender," O.H.G. weih "yielding, soft," Ger. weich "soft," from PIE base *weik- "to bend, wind"

Nezâr "weak, feeble, thin, slim; flesh without fat" (bâde-ye nezâr "a wine with minute alcohol," soxan-e nezâr "inconsistent, weak statement"), variant zâr, Mid.Pers. nizâr (prefixed *ni- + *zâr/*zar) "weak, feeble," Mid./Mod.Pers. zarmân "old man, deterioration," Av. zairina- "exhausting, slackening," zaurura- "weak through old age, decrepit," cf. Skt. jára- "wearing out, exhaustion," jaranā- "old, decayed," jarimán- "weakness through old age," Gk. geron "old man," L. granum "grain;" PIE base *ger- "wear away."
Tâm, → faint.
Sost, from Mid.Pers. sust "weak, lazy."
Kamnur, from kam "little, few; deficient, wanting; scarce" (Mid.Pers. kam "little, small, few," O.Pers./Av. kamna- "small, few") + nur, → light.
Kamzur, from ham + zur, → strength.

weak anthropic principle
  پروز ِ انسان-هستی ِ نزار   
parvaz-e ensân-hasti-ye nezâr

Fr.: principe anthropique faible   

A version of the → anthropic principle whereby the initial conditions in the → Universe are → constrained by the fact that → intelligent life has appeared.

weak; → anthropic; → principle.

weak arm spiral galaxy
  کهکشان ِ مارپیچ با بازوی ِ نزار   
kahkešân-e mârpic bâ bâzu-ye nezâr

Fr.: galaxie spirale à faibles bras   

A gas-rich galaxy that has weak stellar → spiral arms with → interarm gas and star formation more important than a typical → spiral galaxy, such as NGC 4414.

weak; → arm; → spiral; → galaxy.

weak emission-line central star (wel)
  ستاره‌ی ِ مرکزی با خط ِ گسیلی ِ نزار   
setâre-ye markazi bâ xatt-e gosili-ye nezâr

Fr.: étoile centrale à faibles raies d'émission   

A member of a class of cntral stars of planetary nebula, → CSPN, which have weaker and narrower emission lines than → Wolf-Rayet-like CSPNe (Tylenda et al. 1993, A&AS 102, 595).

weak; → emission; → line.

weak encounter
  رویارویی ِ نزار   
ruyâruyi-ye nezâr

Fr.: rencontre faible   

In a → star cluster, an → encounter that occurs at a distance and produces only very small changes in a star's velocity.

weak; → encounter.

weak equivalence principle
  پروز ِ هموگ‌ارزی ِ نزار   
parvaz-e hamug-arzi-ye nezâr

Fr.: principe d'équivalance faible   

All structureless bodies fall along the same → path in a → gravitational field, independent of their composition. Also known as → universality of free fall. See also: → equivalence principle, → Einstein equivalence principle.

weak; → equivalence; → principle.

weak force
  نیروی ِ نزار، ~ کمزور   
niru-ye nezâr, ~ kamzur

Fr.: force faible   

Same as → weak interaction.

weak; → force.

weak gravitational lensing
  لنزش ِ گرانشی ِ نزار   
lenzeš-e gerâneši-ye nezâr

Fr.: effet de lentille gravitationnelle faible   

A gravitational bending of light by structures in the Universe that distorts the images of distant galaxies. The distortion allows the distribution of → dark matter and its evolution with time to be measured, thereby probing the influence of → dark energy on the growth of structures. Weak gravitational lensing is generally difficult to identify in individual images, in contrast to → strong gravitational lensing (see, e.g., Bartelmann & Peter Schneider, 2001, Phys. Rept. 340, 291).

weak; → gravitational; → lensing.

weak interaction
  اندرژیرش ِ نزار، ~ کمزور   
andaržireš-e nezâr, ~ kamzvr

Fr.: interaction faible   

One of the fundamental forces of nature that accounts for some particle interaction, such as → beta decay (→ radioactivity), the decay of free → neutrons, → neutrino interactions, and so forth. It is short-ranged, dominating at distances of 10-16 cm and occurs at a rate slower than that of the → strong interaction by a factor of about 10-13, hence its name. Although the weak interaction also includes interactions in which no neutrinos are emitted, neutrino emission accompanies all weak interactions of interest to astrophysics. Weak interaction plays an important role in the evolution of the stars from birth to death. For example, the → proton-proton reaction is a weak interaction. Also called → weak force or → weak nuclear force.

weak; → interaction.

weak lensing
  لنزش ِ نزار   
lenzeš-e nezâr

Fr.: effet de lentille faible   

The → gravitational lensing in which the images are only weakly distorted, and do not form wide arcs or multiple image systems. This happens if the → gravitational lens mass in front of a source is not concentrated enough to form multiple images. The resulting small distortions cannot be seen on individual sources, as we do not know their unlensed, "intrinsic" shape. However, if an entire population of background sources is available, the distortions can be revealed, either statistically or by local averaging. See also → strong lensing.

weak; → lensing.

weak nuclear force
  نیروی ِ هسته‌ای ِ نزار، ~ ~ کمزور   
niru-ye hasteyi-ye nezâr, ~ ~ kamzur

Fr.: force nucléaire faible   

Same as → weak interaction.

weak; → nuclear; → force.

weak wind problem
  پراسه‌ی ِ باد ِ نزار، ~ ~ کمزور   
parâse-ye bâd-e nezâr, ~ ~ kamzur

Fr.: problème de faible vent   

The discrepancy between the observed → mass loss rates and the predicted values for → weak-wind O-type stars.

weak; → wind; → problem.

weak-line T Tauri star
  ستاره‌ی ِ T-گاو با خط‌های ِ نزار   
setâre-ye T-Gâv bâ xatthâ-ye nezâr

Fr.: étoile T Tauri à raies faibles   

A T Tauri star that lacks strong emission lines in its optical spectrum, and lacks both strong → stellar wind and → infrared excess. These objects are believed to be → pre-main sequence stars without obvious signs for disk → accretion. Weak-line T Tauri stars result from the evolution of → classical T Tauri stars.

weak; → line; → T Tauri star.

weak-wind O-type star
  ستاره‌ی ِ O با باد ِ نزار، ~ ~ ~ ~ کمزور   
setâre-ye O bâ bâd-e nezâr, ~ ~ ~ ~ kamzur

Fr.: étoile O de faible vent   

A → main sequence → O star with low luminosity and surprisingly weak → stellar wind compared to "classical" dwarfs. The → mass loss rates are lower than 10-8 solar masses per year and the → modified wind momenta nearly 2 orders of magnitude smaller than that expected from wind models for typical O stars. Weak-wind O-type stars occur in both → metal-rich and → metal-poor environments. Their nature is not yet fully understood. same as → weak wind problem.

weak; → wind; → O-type star.