Back formation from incline, → inclination.
Šib, → slope.
21 cm line
xatt-e 21-sântimetr (#)
Fr.: raie 21-cm
The → emission line of → neutral hydrogen in → interstellar clouds. It lies in the → radio spectrum at → wavelength of about 21 cm, → frequency 1420 MHz. Its existence was predicted by Hendrik van de Hulst in 1944 and discovered by Harold Ewen and Edward Purcell in 1951.
xatt-e 21-sântimetr (#)
Fr.: raie 21-cm
The → emission line of → neutral hydrogen in interstellar clouds. It lies in the radio spectrum at wavelength of about 21 cm, frequency 1420 MHz. Its existence was predicted by Hendrik van de Hulst in 1944 and discovered by Harold Ewen and Edward Purcell in 1951.
Fr.: raie d'absorption
A dark line in the spectrum of a source produced by a lower temperature gas cloud lying between the source and the observer.
Fr.: raie alcaline
A spectral line produced by an → alkali metal.
From alkal(i) + -ine a suffix denoting "of or pertaining to," "of the nature of," "like."
From qalyâ, → alkali, + -yi adj. suffix.
alkaline earth metal
felez-e qalyâyi-ye xâki (#)
Fr.: terre alcaline
Any of the metallic chemical elements belonging to group 2 of the → periodic table; i.e. → beryllium, → magnesium, → calcium, → strontium, → barium, and → radium. They are not found free in the nature because they are highly reactive.
apsides, line of
Fr.: ligne des apsides
The line connecting the two apsides, i.e. the major axis of an elliptical orbit. → apsis.
Fr.: raie aurorale
1) A prominent → forbidden line in the spectra of
the aurora at wavelengths of 5577 and 6300 Å giving the aurora its characteristic green and
Both are emitted by atomic oxygen, the former in its transition from the
second lowest excited electronic state (1S) to the lowest
excited electronic state (1D), the latter in its transition
from the lowest excited electronic state (1D) to the atomic
ground state (3P).
Fr.: raies de Balmer
Fr.: ligne de base
1) In radio interferometry, the separation between the electrical,
or phase centers of two interferometer elements.
Fr.: ligne de naissance
The path in the → H-R diagram that continuously → accreting stars follow. Stars on the birthline are difficult to observe, because they are hidden by the → accretion disk and a dense → cocoon of → interstellar matter. The star becomes visible once a sufficient amount of the surrounding matter has been dispersed. It follows that the young starsare observed generally between the birthline and the → zero-age main sequence (ZAMS). Before hydrogen ignition, gravitational contraction and deuterium burning are the main energy sources for the star. The localization of the birthline depends on the deuterium → accretion rate. First introduced by R. Behrend & A. Maeder, 2001 (A&A 373, 190).
xatthâ-ye tuham, tânhâ-ye ~
Fr.: raies mélangées
→ Spectral lines intermingled.
broad-line radio galaxy (BLRG)
radio kahkašân-e pahn-xatt
Fr.: galaxie radio à raies larges
A radio galaxy that shows broad optical emission lines. → broad-line region.
broad-line region (BLR)
Fr.: région à raies larges
The inner region of a → quasar or an → active galactic nucleus exhibiting broad → spectral lines which indicate ionized matter moving with speeds in excess of 10,000 km sec-1, probably due to the presence of an → accretion disk surrounding a → supermassive black hole. Also called Type I AGN. See also → obscuring torus.
xatt-e šekasté (#)
Fr.: ligne brisée
A system of connected line → segments joined end to end.
Lying on the same straight line. Collinear points are a set of points on the same line.
Fr.: forces collinéaires
A system of two or more forces that lie along the same → line of action.
A mathematical property where all points lying on a line initially still lie on a line after transformation.
congruent line segments
Fr.: segments congru
Two line segments if they have the same length. They need not lie at the same angle or position on the plane.