bolandi-ye sedâ (#)
Fr.: sonie, force
The magnitude of the sensation produced by a sound wave when it reaches the ear. The loudness of a sound depends upon the effective → acoustic pressure and → frequency. The basis of loudness scales is the → Weber-Fechner law.
A device in which electric signals are converted into audible sound.
→ loud, + agent noun of speak M.E. speken, O.E. specan, variant of sprecan "to speak" (cf. O.S. sprecan, M.Du. spreken, O.H.G. sprehhan, Ger. sprechen "to speak," O.N. spraki "rumor, report").
Bolandgu, from boland, → loud + gu agent noun of goftan "to speak, to say," from Mid.Pers. guftan "to say, tell, utter;" O.Pers. gaub- "to say."
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.
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."
Fr.: faible décalage vers le rouge
A redshift characterizing a near-by receding object.
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 surface brightness galaxy (LSBG)
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.
owpas (#), jazr (#)
Fr.: marée basse
The state of the → tide when at its lowest level.
Fr.: marée basse
Also known as → low tide.
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.
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 nuclear emission-line region
nâhiye-ye hasteyi bâ xatt-e gosili-ye kamyoneš (#)
Fr.: Noyau de galaxie à raies d'émission de faible ionisation
Same as → LINER.
Fr.: fibre à faible perte
Optical fiber that transmits a greater percentage of input light than does high-loss step-index fiber.
Fr.: galaxie de faible masse
A galaxy with stellar masses ≤ 109 → solar masses (Dawn K. Erb, 2015, Nature, 9 July).
setâre-ye kamjerm (#)
Fr.: étoile de faible masse
low-mass X-ray binary (LMXB)
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.
Fr.: environnement faible en métaux
A medium in which chemical elements have abundances smaller than the solar values.
Relatively low in position, rank, or order.
Comparative of → low.
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).
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 main sequence
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.