An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 3106 Search : on
vector boson
  بوسون ِ برداری   
boson-e bordâri

Fr.: boson vectoriel   

In nuclear physics, a → boson with the spin quantum number equal to 1.

vector; → boson.

vector function
  کریای ِ برداری   
karyâ-ye bordâri

Fr.: fonction vectorielle   

A function whose value at each point is n-dimensional, as compared to a scalar function, whose value is one-dimensional.

vector; → function.

vector meson
  مسون ِ برداری   
mesoon-e bordâri

Fr.: meson vectoriel   

Any particle of unit spin, such as the W boson, the photon, or the rho meson.

vector; → meson.

vector perturbation
  پرتورش ِ برداری   
partureš-e bordâri

Fr.: perturbation vectorielle   

The perturbation in the → primordial Universe plasma caused by → vorticity. These perturbations cause → Doppler shifts that result in → quadrupole anisotropy.

vector; → perturbation.

vegetation
  گیاهش   
giyâheš

Fr.: végétation   

1) All the plants or plant life of a place.
2) (Botany) Plant life as a whole, especially the plant life of a particular region.
3) The act or process of vegetating.

Verbal noun from → vegetate.

velocity dispersion
  پاشش ِ تندا   
pâšeš-e tondâ

Fr.: dispersion de vitesses   

The → standard deviation of a velocity → distribution. It indicates how objects of the sample move relative to one another. Objects with similar velocities have a small velocity dispersion, whereas objects with very different velocities have a large velocity dispersion.

velocity; → dispersion.

velocity-distance relation
  باز‌آنش ِ تندا-دورا   
bâzâneš-e tondâ-durâ

Fr.: relation vitesse-distance   

The linear relation wherein all galaxies are moving away from one another, with velocities that are greater with increasing distance of the galaxy. Same as → Hubble's law.

velocity; → distance; → relation.

vena contracta
  شاره‌گذر ِ ترنگیده   
šâre-gozar-e terengidé

Fr.: veine contractée   

The location in a → fluid stream where the → cross section of the → stream is at a minimum, and fluid velocity is the highest, such as in the case of a → jet issuing out of a → nozzle.

L. vena "channel;" contracta, "contracted," → contract.

Šâre-gozar "fluid passage," → fluid; → passage, terengidé, → contracted.

Venus rotation
  چرخش ِ ناهید   
carxeš-e nâhid

Fr.: rotation de Vénus   

The → sidereal rotation period of Venus, or its → sidereal day, is 243.025 Earth days (retrograde). The length of a → solar day on Venus (that is one entire day-night period) is 116.75 Earth days, that is significantly shorter than the sidereal day because of the retrograde rotation. One Venusian year is about 1.92 Venusian solar days.

Venus; → rotation.

verification
  راست-جُست   
râst-jost

Fr.: vérification   

The act of verifying. The state of being verified.
The process of research and examination required to establish correctness, authenticity, or validity.

Verbal noun of → verify.

version
  گرداک   
gardâk

Fr.: version   

A particular form or variant of something.
An account of something, given from a specific point of view.

M.E., from M.Fr. version, from M.L. versionem (nominative versio) "a turning," from p.p. stem of L. vertere "to turn;" cognate with Pers. gardidan "to change," as below.

Gardâk, present stem of gardidan "to change, to turn" (Mid.Pers. vartitan "to change, to turn;" Av. varət- "to turn, revolve;" cf. Skt. vrt- "to turn, roll," vartate "it turns round, rolls;" L. vertere "to turn;" O.H.G. werden "to become;" PIE base *wer- "to turn, bend") + -âk noun suffix.

very-long-baseline interferometry (VLBI)
  اندرزنش‌سنجی با پایه-خط ِ بسیار بزرگ   
andarzanešsanji bâ pâye-xatt-e besyâr bozorg

Fr.: interférométrie à très longue base   

A technique in radio interferometry in which the individual telescopes are not directly connected together, but instead make their observations separately with very accurate timings. The data are later sent to a central correlator to be combined. With this technique the individual telescopes can be arbitrarily far apart, and so the technique provides the highest resolution images in astronomy, typically down to a few milliarcseconds.

very; → large; → baseline; → interferometry.

vibration
  شیوش   
šiveš (#)

Fr.: vibration   

1) The act of vibrating. The state of being vibrated.
2) A continuing → periodic  → oscillation relative to a fixed reference point or → equilibrium state.

Verbal noun from → vibrate.

vibrational
  شیوشی   
šiveši (#)

Fr.: vibrationnel   

Of or pertaining to → vibration. → vibrational mode.

vibration; → -al.

vibrational energy
  کاروژ ِ شیوشی   
kâruž-e šiveši

Fr.: énergie de vibration, ~ vibratoire   

The energy due to the vibration of the molecules making up atoms (→ molecular vibration). A molecule in space can have energies in various forms: → rotational energy, vibrational energy, or electronic energy. These energies of molecules are → quantized and a particular molecule can exist in different rotational and vibrational → energy levels. The molecules can move from one level to another level only by a jump involving a finite amount of energy. → Quantum mechanics predicts that any molecule can never have zero vibrational energy, that is atoms can never be completely at rest relative to each other. The harmonically oscillating molecules can undergo vibrational changes determined by simple selection rules obtained from → Schrödinger equation.

vibrational; → energy.

vibrational frequency
  بسامد ِ شیوشی   
basâmad-e šiveši (#)

Fr.: fréquence de vibration, ~ vibrationnelle   

The frequency at which the atoms in a molecule vibrate. The frequencies of → molecular vibrations in diatomic molecules are in the order of 10-12 to 10-14 Hz. In such molecules, the only → vibrational mode available is along the bond. More complicated molecules have many types of vibration and stretching modes.

vibrational; → frequency.

vibrational mode
  ترز ِ شیوشی   
tarz-e šiveši

Fr.: mode de vibration, ~ vibratoire   

Any of the ways in which a → molecule vibrates. Each vibrational mode has a different → frequency frequency. The number of vibrational modes of a molecule is determined by the number of atoms in it. The number of vibrational modes for a non-linear molecule is 3N - 6, where N is the number of atoms making up the molecule. For a linear molecule it is 3N - 5.

vibrational; → mode.

vibrational transition
  گذرش ِ شیوشی   
gozareš-e šiveši

Fr.: transition vibrationnelle   

A transition between two → quantized  → levels of a → molecule that have different vibrational energies.

vibrational; → transition.

vibrational-rotational transition
  گذرش ِ چرخشی-شیوشی   
gozareš-e carxeši-šiveši

Fr.: transition vibrationnelle-rotationnelle   

A slight change in the → energy level of a → molecule due to → vibrational transition and/or → rotational transition.

vibrational; → rotational; → transition.

violation
  اناه، اناهش   
enâh, enâheš

Fr.: violation   

The act of violating. The state of being violated. → parity violation

Verbal noun from → violate.


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