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

Number of Results: 12 Search : broad
broad
  پهن   
pahn (#)

Fr.: large   

Wide in extent from side to side.

M.E. bro(o)d, from O.E. brad; cf. O.N. breiðr, Du. breed, Ger. breit, Goth. brouþs.

Pahn "wide, broad," from Mid.Pers. pah(a)n; Av. paθana- "broad, wide, spacious;" PIE root *pete- "to spread;" cf. L. patere "to be open," Gk. petannynai "to spread out," petalon "a leaf."

broad-band photometry
  شیدسنجی ِ پهن-باند   
šidsanji-ye pahn-bând

Fr.: photométrie à bande large   

Photometric measurements carried out through filters with a band-width (about one-tenth the central wavelength) in the range 30-100 nm. Typical examples are Johnson photometry, Krons-Cousins RI photometry, and the six-color system.

broad; → band; → photometry.

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.

broaden
  پهنیدن   
pahnidan

Fr.: élargir   

To make or become broad or broader.

borad.

Pahnidan, from pahn, → broad, + -idan infinitive suffix.

broadening
  پهنش   
pahneš

Fr.: élargissement   

The act of making something wider. → instrumental broadening; → line broadening.

Broadening, from → broad + → -ing noun froming suffix.

Pahneš, from pahn (→ broad, present tense stem of pahnidan "to broaden" + -idan infinitive suffix) + verbal-noun suffix.

Doppler broadening
  پهنش ِ دوپلر   
pahneš -e Doppler

Fr.: élargissement Doppler   

In atomic physics, the broadening of an emission or absorption line due to the Doppler effect. Random motions of molecules or atoms of the gas that is emitting or absorbing the radiant energy shift the apparent wavelength of each emitter, and the cumulative effect of indivisual shifts is to broaden the line.

Doppler effect; → broadening.

instrumental broadening
  پهنش ِ سازالی   
pahneš-e sâzâli

Fr.: élargissement instrumental   

The broadening of a point source caused by the response functions of the telescope and the instrument used.

instrumental; → broadening.

line broadening
  پهنش ِ خط   
pahneš-e xatt

Fr.: élargissement de raie   

A widening of → spectral lines due to any of several factors, including the → Doppler broadening, → instrumental broadening, → microturbulence, → pressure broadening, → rotational broadening, the → Stark effect, and the → Zeeman effect.

line; → broadening.

natural line broadening
  پهنش ِ زاستاری ِ خط   
pahneš-e zâstâri-ye xatt

Fr.: élargissement naturel de raie   

The broadening of any spectral line due to the fact that excited levels have mean lives, which, by virtue of the uncertainty principle, implies a spread in the energy values.

natural; → line; → broadening.

pressure broadening
  پهنش ِفشاری   
pahneš-e fešâri

Fr.: élargissement par pression   

A broadening of spectral lines caused mainly by the stellar atmospheric density and the surface gravity of the star. The line strength of a spectral line depends on the number of atoms in the star's atmosphere capable of absorbing the wavelength in question. For a given temperature, the more atoms there are, the stronger and broader the spectral line appears. Denser stars with higher surface gravity will exhibit greater pressure broadening of spectral lines.

pressure; → broadening.

rotational broadening
  پهنش ِ چرخشی   
pahneš-e carxeši

Fr.: élargissement rotationnel   

The spectral line broadening caused by stellar rotation. Light from two rims of the star will be Doppler shifted in opposite directions, resulting in a line broadening effect. The line broadening depends on the inclination of the star's pole to the line of sight. The derived value is a function of ve. sini, where ve is the rotational velocity at the equator and i is the inclination, which is not always known. The fractional width (Δλ/λ) is of the order of 10-3 for B stars.

rotational; → broadening.