An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 502
tord (#)

Fr.: cassant, friable   

A → substance that has a low → elastic limit. For example → glass, which breaks if its low elastic limit is exceeded.

M.E. britel, from brit-, akin to O.E. brytan "to crush, break to pieces," + -el adj. suffix.

Tord "brittle, fragile;" ultimately from Proto-Ir. *tard- "to split, pierce;" related to tâlidan (Dehxodâ) "to spoliate, plunder," eftâlidan "to tear, break," → dissipate; cf. Shughni tidarδ- "to tear, pluck," zidarδ- "to tear, break;" Skt. tard- "to split, to pierce."

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.


Fr.: élargir   

To make or become broad or broader.


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


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.

Brocchi's Cluster
  خوشه‌ی ِ بروکی   
xuše-ye Brocchi

Fr.: amas de Brocchi   

Same as the → Coathanger and Collinder 399.

Named after the American amateur astronomer D. F. Brocchi who created a map of the cluster in the 1920s for calibrating photometers; → cluster.

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.

brom (#)

Fr.: brome   

The only liquid non-metallic chemical element; symbol Br. → Atomic number 35; → atomic weight 79.904; → melting point -7.2°C; → boiling point 58.78°C; → specific gravity of liquid 3.12 at 20°C; → valence -1, +1, +3, +5, or +7. A member of the halogen group of elements. Volatilizes readily at room temperature to a red vapor with strong disagreeable odor and very irritating effect on the eyes and throat. Occurs in combination with various metals, as potassium, sodium and magnesium bromides, which are found in mineral waters, in river and sea-water, and occasionally in marine plants and animals. Its compounds are widely used in photography and medicine. Discovered by Antoine-Jerome Balard (1802-1876) in 1826. Its two stable → isotopes are 79Br (50.69%) and 81Br (49.31%).

From Fr. brome, from Gk. bromos for "stench, bad odor," coined by its discoverer.

Brom, loan from Fr., as above.

  برنز، مفرغ   
boronz (#), mefraq (#)

Fr.: bronze   

A class of → alloys in which → copper and → tin are the dominant elements. The name is extended by usage to include many other copper-rich alloys containing → phosphorus, → manganese, → aluminium, or → silicon.

From Fr. bronze, from It. bronzo, from M.L. bronzium, of unknown origin, maybe from Iranian, cf. Mid.Pers. brinj "bronze, brass;" Mod.Pers. berenj "brass."

Boronz, loan from Fr., as above. Mefraq, from Ar.

Bronze Age
  عصر ِ برنز   
asr-e boronz (#)

Fr.: âge du fer   

A period of time between the → Stone Age and the → Iron Age when bronze was used widely to make tools, weapons, and other implements. The Bronze Age starts at different areas of the world at different times. The earliest use of bronze for making farm tools and weapons are found in Near and Middle East and date back to about 3700 BC. The Bronze Age starts about 2300 BC in Europe.

bronze; → age.

barâdar (#)

Fr.: frère   

Son of the same parents as another person.

M.E.; O.E. brothor; cognate with Du. broeder, Ger. Bruder, Goth. brothar, Skt. bhrātr, Gk. phrater, L. frater, Pers. barâdar, as below, Rus. brat; PIE *bhrater.

Barâdar, from Mid.Pers. brât(ar) "brother;" O.Pers. brata-; Av. brātar- "brother;" cognate with E. brother, as above.

qahve-yi (#)

Fr.: brun   

A dusky color between red and black.

M.E. broun, from O.E. brun "dark," cf. Du. bruin, Ger. braun; PIE base *bher- "shining, brown," related to *bheros "dark animal" (cf. beaver, bear).

Qahvei-yi, color of qahvé "coffee."

brown dwarf
  کوتوله‌ی ِ قهوه‌ای   
kutule-ye qahvei

Fr.: naine brune   

A star-like object whose mass is too small to sustain → hydrogen fusion in its interior and become a star. Brown dwarfs are → substellar objects and occupy an intermediate regime between those of stars and giant planets. With a mass less than 0.08 times that of the Sun (about 80 → Jupiter masses), nuclear reactions in the core of brown dwarfs are limited to the transformation of → deuterium into 3He. The reason is that the cores of these objects are supported against → gravitational collapse by electron → degeneracy pressure (at early spectral types) and → Coulomb pressure (at later spectral types). Brown dwarfs, as ever cooling objects, will have late M dwarf spectral types within a few Myrs of their formation and gradually evolve as L, T and Y dwarfs → brown dwarf cooling. As late-M and early-L dwarfs, they overlap in temperature with the cool end of the stellar → main sequence (→ M dwarf, → L dwarf, → T dwarf, → Y dwarf). In contrast to the OBAFGKM sequence, the M-L-T-Y sequence is an evolutionary one. These objects were first postulated by Kumar (1963, ApJ 137, 1121 & 1126) and Hayashi & Nakano (1963, Prog. Theor.Phys. 30, 460).

The term brown dwarf was first used by Jill Tarter in her 1975 PhD thesis; → brown; → dwarf.

brown dwarf cooling
  سردش ِ کوتوله‌ی ِ قهوه‌ای   
sardeš-e kutule-ye qahve-yi

Fr.: refroidissement de naine brune   

The process whereby a → brown dwarf cools over time after the → deuterium burning phase, which lasts a few 107 years. The → effective temperature and luminosity decrease depending on the mass, age, and → metallicity. Even though massive brown dwarfs may start out with star-like luminosity (≥ 10-3solar luminosities), they progressively fade with age to the point where, after 0.5 Gyr all → substellar objects are less luminous than the dimmest, lowest mass stars. More explicitly, brown dwarfs may start as star-like objects hotter than 2200 K, with → M dwarf spectral types, and, as they get older, pass through the later and cooler L, T, and Y spectral types (→ L dwarf, → T dwarf, → Y dwarf).

brown; → dwarf; → cooling.

brown dwarf desert
  کویر ِ کوتوله‌های ِ قهوه‌ای   
kavir-e kutulehâ-ye qahvei

Fr.: désert des naines brunes   

The observational result indicating a deficit in the frequency of → brown dwarf companions to Sun-like stars, either relative to the frequency of less massive planetary companions or relative to the frequency of more massive stellar companions. However, this desert exists mainly for low-separation brown dwarfs detected using orbital velocity surveys. No brown dwarf desert is noticed at wide separations (J. E. Gizis et al. 2001, ApJ 551, L163).

brown; → dwarf; → desert.

Brownian motion
  جنبش ِ براؤنی   
jonbeš-e Brawni

Fr.: mouvement brownien   

The continuous random motion of solid microscopic particles immersed in a fluid, which is due to bombardment by the atoms and molecules of the medium. It is named after the botanist Robert Brown, who in 1827 first noticed that pollen seeds suspended in water moved in an irregular motion. While there were suspicions that the motion was caused by the collision of atoms against the particles, the first quantitative explanation of the phenomenon, based on the kinetic theory of gases, was forwarded by A. Einstein in 1905. When Einstein's paper appeared, the notion of atoms and molecules was still a subject of heated scientific debate. Ernst Mach and the physical chemist Wilhelm Ostwald were among those who chose to deny their existence.

Named after Robert Brown (1773-1858), a Scottish botanist, who first in 1827 noticed the erratic motion of pollen grains suspended in water. → motion.

Brunt-Vaisala frequency
  بسامد ِ برانت-وایسالا   
basâmad-e Brunt-Väisälä

Fr.: fréquence de Brunt-Väisälä   

The frequency at which an air parcel will oscillate when subjected to an infinitesimal perturbation in a stably stratified atmosphere. For a medium with a continuous density gradient, it is expressed by the formula: N2 = -(g/ρ)∂ρ/∂z , where g is the → gravitational acceleration, ρ is density, and z geometric height. The stability condition is N > 0. It is also sometimes referred to as the buoyancy frequency. The higher the value of N the more stable the flow.

Named aster David Brunt (1886-1965), British meteorologist (1927, Q.J.R.Met.Soc. 53, 30) and Vilho Väisälä (1889-1969), Finnish meteorologist (1925, Soc. Sci. Fenn. Commental. Phys. Math. 2 (19), 19); → frequency.

  تنگل، حباب   
tangol, hobâb

Fr.: bulle   

General:A small body of gas within a liquid; a thin film of liquid inflated with air or gas.
Astro.: 1) Bubble-like structures of hot ionized gas created in the interstellar medium by the action of the powerful winds of massive stars.
2) A giant bubble-like component appearing during the growth of large-scale structures in the early Universe.

Bubble, from M.E. bobel, perhaps from M.Du. bobbel.

Tangol "bubble," from štiyâni dialect, maybe from tan "body" + gol "flower," literally "that which has a delicate body (like a flower)." This etymology is derived from the observation that in Pers. bubble is often likened to a flower: qonce-ye âb, kupale-ye âb, quze-ye âb [Dehxodâ] "water blossom, water flower, water bud."
Hobâb, from Ar. habâb.

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