An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < -ab ab- abo abs abs acc acc acr act ada adh Adr aer age Air Alf alg all alp alt ama amp ana ang ang ann ano ant ant apl Apo app Aqu arc arg arr ASC ass ast ast asy atm att aur aut axi > >>

Number of Results: 916
alpha effect
  اسکر ِ آلفا   
oskar-e Alfâ

Fr.: effet α   

In the → solar dynamo model, the process whereby the → azimuthal magnetic field transforms into a → meridional magnetic field due to the interaction of → convection and → differential rotation. See also → omega effect.

alpha; → effect.

alpha element
  بن‌پار ِ آلفا   
bonpâr-e âlfâ

Fr.: élément α   

A → chemical element synthesized in → massive stars by → alpha particle capture leading to iron before the advent of a → type II supernova. Stable alpha elements are: C, O, Ne, Mg, Si, S, Ar, Ca.

alpha; → element.

alpha element knee
  زانوی ِ بن‌پار ِ آلفا   
zânu-ye bonpâr-e âlfâ


The point in the plot showing → alpha element abundances ([α/Fe]) of a galaxy as a function of the → metallicity ([Fe/H]) where the α-element abundance drops. The metallicity of the turn-over in α-element abundances is linked to the → star formation rate during the early stage of star formation in a galaxy and therefore also depends on the total mass of the system. Higher star formation efficiency leads to higher overall metallicity before the onset of → Type Ia supernova → enrichment, and thus to a knee that is located at higher [Fe/H] values.

alpha; → element; → knee.

alpha emission
  گسیل ِ آلفا   
gosil-e âlfâ

Fr.: émission alpha   

The release of → alpha particles at high velocity from an atom's nucleus as it undergoes radioactive transformation.

alpha; → emission.

alpha emitter
  گسیلنده‌ی ِ آلفا   
gosilandé-ye âlfâ

Fr.: émetteur d'alpha   

An atomic nucleus decaying by an → alpha particle emission.

alpha; → emitter.

alpha ladder
  نردبان ِ آلفا   
nardebân-e âlfâ

Fr.: échelle aplpha   

alpha process.

alpha; → ladder.

alpha offset
  اپنه ِ آلفا   
apneh-e Âlfâ

Fr.: offset en ascension droite   

A short distance from the target, in right ascension, where the telescope is pointed for various purposes.

alpha; → offset.

alpha particle
  ذره‌ی ِ آلفا   
zarre-ye Âlfâ

Fr.: particule alpha   

A positively charged particle emitted from the nuclei of certain atoms during radioactive disintegration. The alpha particle has an atomic weight of 4 and a positive charge equal in magnitude to 2 electronic charges; hence it is essentially a helium nucleus.

alpha; → particle.

alpha process
  فراروند ِ آلفا   
farâravand-e âlfâ

Fr.: processus α   

A class of → nuclear fusion reactions by which stars convert → helium into → heavy elements. Once carbon has been created, through → triple alpha process, in a star's interior, it can then continue to fuse with further → alpha particles to produce progressively heavier elements called → alpha particles. The first stage produces oxygen, followed by neon, magnesium, silicon, sulfur, argon, calcium, titanium, chromium and iron. This is known as the → alpha ladder, with energy released as a photon at each stage.

alpha;→ process.

Alphard (α Hydrae)
Alfard (#)

Fr.: Alphard   

The only bright star in the constellation → Hydra, that has a magnitude of about 2 and a reddish color. Alphard is a giant of spectral type K3, and has a → white dwarfcompanion. Alphard is mild barium star probably contaminated by its companion before becoming a white dwarf.

Alphard, from Ar. Al-Frad ash-Shuja' "the solitary of the Serpent," from Frad "solitary" + Shuja' "a species of serpent".

Alphekka (α Coronae Borealis)
Alfakké (#)

Fr.: Alphekka   

Also known as Gemma, the brightest star in Corona Borealis (visual magnitude 2.23). Alphekka is an A type dwarf lying at about 7 → light-years. Actually it has a faint Sun-like (G5 V) companion, that produces an eclipse of the primary every 17.4 days.

Alphekka, from Ar. Nayyir al-Fakkah "the bright of the broken" (ring of star), from Nayyir "bright" + fakkah "broken," from fakk "to disjoin, unloose".

Alpheratz (α Andromedae)

Fr.: Alphératz   

The brightest star in → Andromeda with a visual magnitude of 2.07. Alpheratz is a blue → subgiant star of spectral type B8 IV lying at a distance of about 97 → light-years. It is particularly remarkable because of the unusual strength of mercury and manganese absorption lines in its spectrum.

Other names for this star are Alpherat, Sirrah, or Sirah. These names derive from Ar. As-Surrat al-Faras (السره‌الفرس) "The Horse's Navel," from surrat (سره) "navel" + faras (فرس) "horse". The name refers to the location of the star in the figure of → Pegasus. However, the star is now considered to belong to the constellation → Andromeda.

Ra's-ol-Mosalsalé, from Ar. Ar-Ra's al-Mar'ah al-Musalsalah "The head of the chained woman," from Ra's "head" + Mar'ah "woman" + Musalsalah "chained".


Fr.: déjà   

1) By this or that time; previously; prior to or at some specified or implied time.
2) Now; so soon; so early (

From M.E. al redy, literally "fully ready," → all, + M.E. redy "ready," from rædig, from O.E. ræde "prompt" + -ig "-y."

Pišnun, literally "prior to now," from piš-, → pre-, + Mid./Mod.Pers. nun "now, at present" (variants aknun, konun, ultimately from Proto-Ir. *hak-nun); Av. nū- "now," nūrəm "now;" O.Pers. nūram "now;" cf. Skt. nú- "now, just, but," nūnám "now, at present, indeed;" Gk. nun "now;" L. nu- "now" (in nu-dis "the day after tomorrow"); Goth. nu "now;" O.E. nu; E. now; PIE base *nu- "now."

Altair (α Aquilae)
  طایر، نسر ِ طایر، کرکس ِ پرنده   
Tâyer, Nasr-e Tâyer, Karkas-e Parandé (#)

Fr.: Altaïr   

The brightest star in → Aquila (apparent visual magnitude 0.77), and the twelfth brightest star in the sky. Altair is a whitish A7 → main sequence star. It has one of the fastest known rotational speeds, 242 km/s at the equator, compared with the Sun's about 2 km/s.

Altair, from Ar. An Nasr at-Taiir "The Flying Vulture," from Nasr "vulture" + Ta'ir "flying."

Karkas-e Parandé "The Flying Vulture" coined by Biruni (around A.D. 1000), from karkas "vulture," Av. kahrkâsa- "devourer hen," from *kahrka "hen" (Mod.Pers. kark "hen," karak "quail") + *âsa "to eat" (Mod.Pers. âš "food, soup") + Parandé "flying," from paridan "to fly" (from Mid./Mod.Pers. par(r) "feather, wing," Av. parəna- "feather, wing;" cp. Skt. parna "feather," E. fern; PIE *porno- "feather").


Fr.: altazimutal   

1) A → mounting for → telescopes that permits both → vertical and → horizontal → rotation.
2) A telescope having such a mounting.
See also: → altazimuth coordinate system, → altazimuth instrument, → altazimuth mounting.

Altazimuth, from alt(itude) + → azimuth.

Farâzâ-sugân, from farâzâ, → altitude, + sugân, → azimuth.

altazimuth coordinate system
  راژمان ِ هم‌آراهای ِ فرازا-سوگان   
râžmân-e hamârâhâ-ye farâzâ-sugân

Fr.: coordonnées azimutales   

The coordinate system in which the position of a body on the → celestial sphere is described with respect to an observer's → celestial horizon and → zenith. The coordinates of a point in this system are its → altitude on the → vertical circle, and its → azimuth westward (clockwise) along the celestial horizon from the observer's south. Same as → horizon coordinate system.

altazimuth; → coordinate; → system.

altazimuth instrument
  سازال ِ فرازا-سوگان   
sâzâl-e farâzâ-sugâni

Fr.: instrument altazimutal   

A telescope that moves vertically along the → altitude circle of a celestial body and horizontally along its → azimuth circle.

altazimuth; → instrument.

altazimuth mounting
  برنشاند ِ فرازا-سوگان   
barnešând-e farâzâ-sugân

Fr.: monture altazimutale   

A → telescope mounting which has its two axes of movement aligned with the → horizon and the → zenith.

mounting; → mounting.

  دگرگون کردن، دگرگونیدن   
degargun kardan, degunidan

Fr.: altérer   

( To change or make different.
(v.intr.) To change or become different.

M.E. alteren, from O.Fr. altérer, from M.L. alterre, from L. alter "other," from PIE *al- "beyond" + comp. suffix -ter.

Degargun kardan, degargunidan, from degargun, from degar, → change, + -gun "manner, fashion," → elliptical, + kardan, -idan, → -ize.

  دگرگونی، دگرگونش   
degarguni, degarguneš

Fr.: altération   

1) The act or process of altering; the state of being altered.
2) The result of altering.

Verbal noun of → alter.

<< < -ab ab- abo abs abs acc acc acr act ada adh Adr aer age Air Alf alg all alp alt ama amp ana ang ang ann ano ant ant apl Apo app Aqu arc arg arr ASC ass ast ast asy atm att aur aut axi > >>