An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 488
  گوییک، گوییکی، گوییکوار   
guyik, gyuiki, guyikvâr

Fr.: logique   

1) According to or agreeing with the principles of logic.
2) Reasoning in accordance with the principles of logic, as a person or the mind.
3) Of or pertaining to logic (

logic; → -al.

logical connective
  هابندار ِ گوییکی   
hâbandâr-e guyiki

Fr.: connecteur logique   

A symbol that can be combined with one or more → sentences in order to form a new sentence. For example "and" (∧), "or" (∨) "not" (¬), "if-then" (→), and "iff" (⇔).

logical; → connective.

logically equivalent
  گوییکانه هموگ‌ارز   
guyikâné hamug-arz

Fr.: logiquement équivalent   

Describing two → compound propositions → if and only if they have the same → truth table.

logical; → equivalent.


Fr.: identification, connexion   

1) The act of logging in to a database, mobile device, or computer, especially a multi-user computer or a remote or networked computer system.
2) A user name and password that allows a person to log in to a computer system, network, mobile device, or user account (

log; → in.

lognormal distribution
  واباژش ِ لگاریتمی-هنجارور   
vâbâžeš-e logâritmi-hanjârvar

Fr.: distribution logarithmico-normale   

A → probability distribution in which the natural logarithm (logX) of the → random variable (X) has a → Gaussian distribution.

logarithm; → normal distribution.


Fr.: fin de session, déconnexion   

The process by which a computer user logs out.

log; → out.

Lomb-Scargle periodogram
  دوره‌نگاشت ِ لومب-اسکارگل   
dowrenegâšt-e Lomb-Scargle

Fr.: périodogramme de Lomb-Scargle   

An algorithm for detecting and characterizing periodic signals in unevenly-sampled data. The Lomb-Scargle periodogram has a particularly wide use within the astronomy community. This method allows efficient computation of a Fourier-like → power spectrum estimator from such unevenly-sampled data, resulting in an intuitive means of determining the period of oscillation (see VanderPlas, 2017, astro-ph/1703.09824 and references therein).

Named after Lomb, N. R. 1976, Ap&SS 39, 447 and Scargle, J. D. 1982, ApJ 263, 835; → periodogram.

derâz (#)

Fr.: long   

1) Having considerable linear extent in space. → very-long-baseline interferometry (VLBI).
2) Having considerable duration in time. → long-period variable.

M.E. longe, O.E. lang, long, akin to O.H.G., Ger. lang "long," O.N. langr, M.Du. lanc, Goth. laggs "long," L. longus, → longitude.

Derâz "long," Mid.Pers. drâz "long;" O.Pers. darga- "long;" Av. darəga-, darəγa- "long," drājištəm "longest;" cf. Skt. dirghá- "lon (in space and time)."

long-period comet
  دمدار ِ درازدوره   
domdâr-e derâz dowré

Fr.: comète à longue période   

A comet with orbital period of more than 200 years. → short-period comet; → periodic comet.

long; → period; → comet.

long-period variable
  ورتنده‌ی ِ درازدوره   
vartande-ye derâz dowré

Fr.: variable à longue période   

A type of → variable star in which variations in brightness occur over long time-scales of months or years. The term generally refers to → Mira variable types.

long; → period; → variable.


Fr.: longitude   

The angular distance on the Earth's surface, measured east or west from the prime meridian at Greenwich to the meridian passing through a position, expressed in degrees (or hours), minutes, and seconds.

L. longitudo "length," from longus "long," cognate with Pers. derâz, as below, Gk. dolikhos "elongated;" O.H.G., Ger. lang, O.N. langr, M.Du. lanc, Goth. laggs "long;" PIE base *dlonghos- "long."

Derežnâ, from derež (Kurdi, Laki), variants darg "length; long, tall" (Zâzâ), darγ (Ossetic), derâz "long" + -nâ noun forming suffix from adjective, as in derâznâ, pah(n)nâ, farâxnâ, tangnâ, tiznâ. The first element from Mid.Pers. drâz "long;" O.Pers. darga- "long;" Av. darəga-, darəγa- "long," drājištəm "longest;" cf. Skt. dirghá- "lon (in space and time);" PIE *dlonghos- "long," as above.

longitude of ascending node
  درژنای ِ گره ِ فرازشی   
derežnâ-ye gereh-e farâzeši

Fr.: longitude du nœ ud ascendant   

One of the → orbital elements used to specify the orbit of an object in space. It is the angle from the reference direction, called the origin of longitude, to the direction of the → ascending node, measured in the reference plane.

longitude; → ascending node.


Fr.: longitudinal   

Of or pertaining to longitude or length. Extending in the direction of the length.

Adj. of → longitude.

longitudinal magnetic field
  میدان ِ مغناطیسی ِ درژنایی   
meydân-e meqnâtisi-ye derežnâyi

Fr.: champ magnétique longitudinal   

1) A → magnetic field whose lines of force (→ line of force) run parallel to the long axis of the → magnet. Longitudinal magnetization of a component can be accomplished using the longitudinal field set up by a → coil or → solenoid. It can also be accomplished using permanent magnets or electromagnets.
2) In → stellar magnetic field observations, the magnetic field along the → line of sight.

longitudinal; → magnetic; → field.

longitudinal mass
  جرم ِ درژنایی   
jerm-e derežnâyi

Fr.: masse longitudinale   

In special relativity theory, the mass of a body when the acceleration is parallel or anti-parallel to velocity: ml = m0 / [1 - (v/c)2]3/2, where m0 is the → rest mass, v is the velocity, and c the → velocity of light. → transverse mass.

longitudinal; → mass.

longitudinal wave
  موج ِ درژنایی   
mowj-e derežnâyi

Fr.: onde longitudinale   

A wave vibrating along the direction of propagation, such as a → sound wave. → transverse wave.

longitudinal; → wave.

longitudinal Zeeman effect
  اُسکر ِ زیمن ِ درژنایی   
oskar-e Zeeman-e derežnâyi

Fr.: effet Zeeman longitudinal   

The → Zeeman effect when the emitting source is viewed in the direction of the magnetic field. In the normal longitudinal effect, each spectral line is split into two components with frequencies ν ± Δν. The line with the frequency ν - Δν shows left-hand → circular polarization and that with frequency ν + Δν shows right-hand circular polarization. → transverse Zeeman effect.

longitudinal; → Zeeman effect.

negâh (#)

Fr.: regard   

The act or instance of looking.

Look, from W.Gmc. *lokjan (cf. O.S. lokon, M.Du. loeken, O.H.G. luogen, Ger. dialectal lugen "to look out"), of unknown origin.

Negâh "look," from Mid.Pers. nikâh "look, glance, observation;" Proto-Iranian *ni-kas- "to look down," from ni- "down," → ni- (PIE), + *kas- "to look, appear;" cf. Av. nikā-, nikāta- (in the name of the 15-th nask) "that which is observed," ākas- "to look;" Mid.Pers. âkâh, Mod.Pers. âgâh "aware, knowing;" Skt. kāś- "to become visible, appear;" Ossetic kast/kaesyn "to look."

look-back time
  زمان ِ نگاه به گذشته   
zamân-e negâh bé gozašté

Fr.: temps de retour en arrière   

The time that has elapsed since the light was emitted from a distant object (of → redshift z). Because → light moves at a → constant  → speed, it takes a finite time to travel from distant objects. Hence, we "see" distant objects at a point in time in their past. In other words, look-back time is the difference between the age of the Universe now and the age of the Universe at the time the photons were emitted from the object. See also → comoving distance.

look; → back; → time.

Zamân, → time; negâh, → look; gozašté "past, passed" (from gozaštan "to pass, proceed, go on," variant gozâštan "to put, to place, let, allow;" Mid.Pers. widardan, widâštan "to pass, to let pass (by);" O.Pers. vitar- "to pass across," viyatarayam "I put across;" Av. vi-tar- "to pass across," from vi- "apart, away from" (O.Pers. viy- "apart, away;" Av. vi- "apart, away;" cf. Skt. vi- "apart, asunder, away, out;" L. vitare "to avoid, turn aside") + O.Pers./Av. tar- "to cross over").


Fr.: boucle   

General: Anything shaped more or less like a loop, i.e. portion of a cord, ribbon, etc., folded or doubled upon itself.
Physics: The part of a vibrating string, column of air or other medium, etc., between two adjacent nodes.
Computers: The reiteration of a set of instructions in a routine or program.

Probably of Celtic origin (cf. Gael. lub "bend," Ir. lubiam), influenced by O.N. hlaup "a leap, run."

Gerdâl, from gerd "round, a circle" (Mid.Pers. girdag "disk, round," from gird/girt "round, all around," Proto-Iranian *gart- "to twist, to wreathe," cf. Skt krt "to twist threads, spin; to wind; to surround;" kata- "a twist of straw," Pali kata- "ring, bracelet," Gk. kartalos "a kind of basket," kyrtos "curved") + → -al.

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