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: 172 Search : line
-cline
     
-šib

Fr.: -cline   

A suffix indicating a slope, as in → barocline, → thermocline, → tachocline.

Back formation from incline, → inclination.

Šib, → slope.

21 cm line
  خط ِ ۲۱ س.م.   
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.

Twenty-one (21); → twenty + → one; → centimeter; → line.

21-centimeter line
  خط ِ ۲۱ س.م.   
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.

Twenty-one (21); → twenty + → one; → centimeter; → line.

absorption line
  خط ِ درشمی   
xatt-e daršami

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.

absorption; → line.

alkali line
  خط ِ قلیایی   
xatt-e qalyâyi

Fr.: raie alcaline   

A spectral line produced by an → alkali metal.

alkali; → line.

alkaline
  قلیایی   
qalyayi (#)

Fr.: alkalin   

Having the properties of an → alkali; having a → pH greater than 7.0.

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
  فلز ِ قلیایی ِ خاکی   
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.

alkaline; → earth; → metal.

Felez, → metal; qalyâyi, → alkaline; xâki "of or pertaining to soil," from xâk, → soil.

apsides, line of
  خط ِ هباک‌ها   
xatt-e habâkhâ

Fr.: ligne des apsides   

The line connecting the two apsides, i.e. the major axis of an elliptical orbit. → apsis.

Apsides, pl. of → apside; → line.

auroral line
  خط ِ اوشه‌ای   
xatt-e uše-yi

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 red colors. 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).
2) A forbidden line emitted by interstellar ionized gas by several atomic species (O, O+, O++, N+, S++, etc.) corresponding to the transition from the state 1S to 1D. → forbidden line; → nebular line; → transauroral line.

auroral; → line.

Balmer line
  خط ِ بالمر   
xatt-e Bâlmer

Fr.: raies de Balmer   

The → spectral lines making up the → Balmer series.

Balmer; → line.

baseline
  پایه-خط   
pâye-xatt

Fr.: ligne de base   

1) In radio interferometry, the separation between the electrical, or phase centers of two interferometer elements.
2) In spectroscopy, the contribution to a spectrum from phenomena that are not of astronomical interest, such as frequency dependent properties of the receivers, or by astronomical sources other than those under study.

base; → line.

birthline
  زاد-خط   
zâd-xatt

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).

birth; → line.

blend lines
  خطهای ِ توهم، تانهای ِ ~   
xatthâ-ye tuham, tânhâ-ye ~

Fr.: raies mélangées   

Spectral lines intermingled.

blend; → line.

broad-line radio galaxy (BLRG)
  رادیو‌کهکشان ِ پهن-خط   
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; → radio galaxy.

broad-line region (BLR)
  ناحیه‌ی ِ پهن-خط   
nâhiye-ye pahn-xatt

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.

broad; → line; → region.

broken line
  خط ِ شکسته   
xatt-e šekasté (#)

Fr.: ligne brisée   

A system of connected line → segments joined end to end.

Past participle of → break; → line.

collinear
  هم-خط   
ham-xatt

Fr.: colinéaire   

Lying on the same straight line. Collinear points are a set of points on the same line.

com- + → linear.

collinear forces
  نیروهای ِ هم-خط   
niruhâ-ye ham-xatt

Fr.: forces collinéaires   

A system of two or more forces that lie along the same → line of action.

collinear; → force.

collinearity
  هم-خطی   
ham-xatti

Fr.: collinéarité   

A mathematical property where all points lying on a line initially still lie on a line after transformation.

collinear; → -ity.

congruent line segments
  برنک‌های ِ دمساز   
borankhâ-ye damsâz

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.

congruent; → line; → segment.

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