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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

   Homepage   
   


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

<< < acc flo lin lun sub > >>

Number of Results: 95 Search : low
line of flow
  خط ِ تچان   
xatt-e tacân

Fr.: ligne d'écoulement   

Same as → streamline.

line; → flow.

low
  ۱) کم، که؛ ۲) کوتاه، پایین   
1) kam (#), keh (#); 2) kutâh (#), pâyin (#)

Fr.: bas, faible   

1) Below the average or expected degree, amount, or intensity. Having or containing a relatively small amount.
2) Situated, placed, or occurring not far above the ground, floor, or base. Relatively little in height.

From M.E. lah, from O.N. lagr "low," from P.Gmc. *lægaz (cf. O.Fris. lech, Du. laag, Ger. läge "low"), literally "that which is lying flat;" related to E. lie (v.).

Kam "little, few; deficient, wanting; scarce," from Mid.Pers. kam "little, small, few," O.Pers./Av. kamna- "small, few."
Keh "small, little, slender" (related to kâstan, kâhidan "to decrease, lessen, diminish," from Mid.Pers. kâhitan, kâstan, kâhênitan "to decrease, diminish, lessen;" Av. kasu- "small, little;" Proto-Iranian *kas- "to be small, diminish, lessen"); kutâh, → small; pâyin, → bottom-up structure.

low redshift
  که‌سرخ‌کیب   
keh sorxkib

Fr.: faible décalage vers le rouge   

A redshift characterizing a near-by receding object.

low; → redshift.

low resolution
  که‌واگشود   
keh vâgošud

Fr.: faible résolution   

The quality of an instrument that lacks sufficient resolution for a specific observation. This is a relative quality, but presently a resolution below about 1 arcsecond.

low; → resolution.

low surface brightness galaxy (LSBG)
  کهکشان با درخشندگی ِ رویه‌ای ِ کم   
kahkešân bâ deraxšandegi-ye ruye-yi-ye kam

Fr.: galaxie à faible brillance de surface   

A member of a particularly faint population of galaxies with a central → surface brightness below the brightness of the background sky. The central regions of many of them resemble a → dwarf galaxy, but most of the mass is contained in a large gaseous disk of low density that is observable only with long-exposure optical images or at radio wavelengths. Some are as massive as a large → spiral galaxy, for example Malin 1. The proportion of LSBGs relative to normal galaxies is unknown. They may however represent a significant fraction of mass in the Universe. LSBGs are thought to be primitive systems because they have total masses similar to normal galaxies, but have typically converted less than 10% of their gas into stars. Spiral LSBGs do not obey → Freeman's law.

low; → surface; → brightness; → galaxy.

low tide
  اوپس، جزر   
owpas (#), jazr (#)

Fr.: marée basse   

The state of the → tide when at its lowest level.

low; → tide.

Owpas, from Persian Gulf dialects, literally "backward water," from ow, variant of âb, → water, + pas "→ back, behind."
Jazr, loan from Ar.

low water
  اوپس، جزر   
owpas, jazr

Fr.: marée basse   

Also known as → low tide.

low; → water.

low-energy neutrino
  نوترینو‌ی ِ کم‌کاروژ   
notrino-ye kamkâruž

Fr.: neutrino faible énergie   

A neutrino which is mainly produced in → nuclear processes, such as the ones in the → Sun (→ solar neutrino), or in the center of an exploding → supernova. Such neutrinos are, however, more energetic than those making up the → cosmic neutrino background.

low; → energy; → neutrino.

low-ionization line
  خط ِ کم‌یونش   
xatt-e kamyoneš (#)

Fr.: raie de faible ionisation   

A spectral line arising from a transition between atomic levels with an ionization potential below approximately 15 electron-volts.

low; → ionization; → line.

low-ionization nuclear emission-line region
  ناحیه‌ی ِ هسته‌ای با خط ِ گسیلی ِ کم‌یونش   
nâhiye-ye hasteyi bâ xatt-e gosili-ye kamyoneš (#)

Fr.: Noyau de galaxie à raies d'émission de faible ionisation   

Same as → LINER.

low; → ionization; → nuclear; → emission; → line; → region.

low-loss fiber
  فیبر ِ کم‌دسترفت   
fibr-e kamdastraft

Fr.: fibre à faible perte   

Optical fiber that transmits a greater percentage of input light than does high-loss step-index fiber.

low; → loss; → fiber.

low-mass galaxy
  کهکشان ِ کم‌جرم   
kahkešân-e kamjerm

Fr.: galaxie de faible masse   

A galaxy with stellar masses ≤ 109 → solar masses (Dawn K. Erb, 2015, Nature, 9 July).

low; → mass; → galaxy.

low-mass star
  ستاره‌ی ِ کم‌جرم   
setâre-ye kamjerm (#)

Fr.: étoile de faible masse   

A star whose mass is around that of the Sun. See also: → intermediate-mass star; → high-mass star; → star formation.

low; → mass; → star.

low-mass X-ray binary (LMXB)
  درین ِ پرتو ایکس ِ کم‌جرم   
dorin-e partow-e iks-e kam-jerm

Fr.: binaire X de faible masse   

A member of one of the two main classes of → X-ray binary systems where one of the components is a → neutron star or → black hole and the other component a → low-mass star with a spectral type A or later. LMXBs mainly emit → soft X-rays. The ratio of their optical to X-ray luminosities is less than 0.1. They belong to → old stellar populations with ages 5-15 × 109 years and are found in → globular clusters and in the → bulge of our → Milky Way galaxy; some are also found in the disk. Hercules X-1 is an example of LMXBs.
See also: → high-mass X-ray binary.

low; → mass; → X-ray; → binary.

low-metallicity environment
  پرگیر ِ کم‌فلز   
pargir-e kamfelez

Fr.: environnement faible en métaux   

A medium in which chemical elements have abundances smaller than the solar values.

low; → metallicity; → environment.

lower
  زیرین   
zirin (#)

Fr.: inférieur   

Relatively low in position, rank, or order.

Comparative of → low.

lower atmosphere
  هواسپهر ِ زیرین، جو ِ ~   
havâsepehr-e zirin, javv-e ~

Fr.: atmosphère inférieure   

Generally and quite loosely, that part of the atmosphere in which most weather phenomena occur (i.e., the → troposphere and lower → stratosphere); hence used in contrast to the common meaning for the → upper atmosphere. In other contexts, the term implies the lower troposphere (Meteorology Glossary, American Meteorological Society).

lower; → atmosphere.

lower culmination
  بالست ِ زیرین   
bâlest-e zirin

Fr.: culmination inférieure   

The instant of culmination when the star passes between the pole and the horizon, having an hour angle of 12h. Lower culmination for non-circumpolar objects occur below the horizon and is thus unobservable. Same as → inferior culmination. See also → upper culmination.

lower; → culmination.

lower main sequence
  رشته‌ی ِ فریست ِ زیرین   
rešte-ye farist-e zirin

Fr.: séquence principale inférieure   

A → main sequence star whose mass is less than 1.5 Msun. Lower main sequence stars generate their energy chiefly through the → proton-proton chain. The core is surrounded by a → radiative zone above which lies a → convective envelope. In such stars the → opacity at the surface is high because of the low → surface temperature. Therefore, radiation cannot carry all the radiation because of high opacity. Thus, energy transfer takes place by → convection to the outer layer.

lower; → main; → sequence.

lower mantle
  گوشته‌ی ِ زیرین   
gušte-ye zirin

Fr.: manteau inférieur   

The part of the Earth's → mantle extending from about 660 km below the surface to above the → outer core at about 2,900 km.

lower; → mantle.

<< < acc flo lin lun sub > >>