An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < -ti tan Tay tem ten Ter the the the the thi thr tid tim Tit top tot tra tra tra tra tri Tri tru Tuc tur Tyc Typ > >>

Number of Results: 544
time of periapsis passage
  زمان ِ گذر از پیراهباک   
zamân-e gozar az pirâhabâk

Fr.: temps de passage au périapse   

One of the → orbital elements, the time when the → secondary body reaches → periapsis.

time; → periapsis; → passage.

time resolution
  واگشود ِ زمانی   
vâgošud-e zamâni

Fr.: résolution temporelle   

Same → temporal resolution.

time; → resolution.

time reversal
  وارونش ِ زمان   
vâruneš-e zamân

Fr.: renversement du temps   

A transformation operating on time in the equations of motion of a dynamical system in which t is replaced by -t.

time; → reversal.

time scale
  مرپل ِ زمان   
marpel-e zamân

Fr.: échelle de temps   

A measure of duration of a specific process, such as → crossing time, → dynamical time scale, → evolutionary time scale, → Kelvin-Helmholtz time scale, → nuclear time scale, → photon escape time, → relaxation time, → star formation time scale.

time; → scale.

time zone
  زنار ِ زمان، زمان-زنار   
zonâr-e zamân, zamân-zonâr

Fr.: fuseau horaire   

Any of the 24 zones on the Earth surface delimited by → meridians at approximately 15° intervals. In each time zone a common standard time is used, and the time is one hour earlier than the zone immediately to the east.

time; → zone.

time's arrow
  پیکان ِ زمان   
peykân-e zamân

Fr.: flèche du temps   

The sequence of all natural processes in which the → entropy increases. In other words, the fact that these processes all move in one direction in time and are → irreversible. The past is distinctly different from the future; things always grow older, never younger.

time; arrow, M.E. arewe, arwe, from O.E. arwan, earh "arrow," from P.Gmc. *arkhwo (cf. Goth. arhwanza), from PIE base *arku- "bow and/or arrow," source of Latin arcus, → arc.

Peykân "arrow," → Sagitta; zamân, → time.


Fr.: genre temps   

Of, pertaining to, or describing an → event belonging to the interior of the → light cone.

time; → like.

timelike interval
  اندروار ِ زمانسان   
andarvâr-e zamânsân

Fr.: intervalle genre temps   

The → space-time interval between two → events if it is real, i.e. ds2 > 0.

timelike; → interval.

zamân-šomâr (#)

Fr.: appareil horaire   

Any mechanical, electric, or electronic device, such as a clock or watch, designed to measure and display the passage of time.

From → time + piece, M.E. pece, O.Fr. piece.

Zamân-šomâr, literally "time counter," from zamântime + šomâr "counter," from šomârdan "to count," from Mid.Pers. ôšmârtan, ôšmurtan "to reckon, calculate, enumerate, account for," from Av. base (š)mar- "to have in mind, remember, recall," pati-šmar- "to recall; to long for," hišmar-, cf. Skt. smar- "to remember, become aware," smarati "he remembers," L. memor, memoria, Gk. mermera "care," merimna "anxious thought, sorrow," martyr "witness."

  ارزیز، قلعی   
arziz (#), qal'y (#)

Fr.: étain   

A metallic chemical element; symbol Sn (L. stannum for → alloys containing → lead). → Atomic number 50; → atomic weight 118.69; → melting point 231.9681°C; → boiling point 2,270°C; → specific gravity 5.75 (gray), 7.3 (white). The element was known in prehistoric times.

M.E., O.E. tin; cf. M.Du., Du. tin, O.H.G. zin, Ger. Zinn, O.N. tin; related to Fr. étain?

Arziz "tin," from Mid.Pers. arziz "tin, lead," arus "white, bright;" Av. ərəzata- "silver," auruša- "white;" cf. Skt. arjuna- "white, shining," rajata- "silver;" Gk. argos "white," arguron "silver," L. argentum "silver," arguere "to make clear," argmentum "argument;" PIE *arg- "to shine, be white, bright, clear."
Qal'y of unknown origin.

TiO band
  باند ِ TiO   
bând-e TiO

Fr.: bandes TiO   

Any of the several → absorption bands due to the molecule → titanium oxide that are prominent in the spectra of cool → K and → M stars.

titanium oxide; → band.

tip of the red giant branch method
  روش ِ نوک ِ شاخه‌ی غول‌های ِ سرخ   
raveš-e nok-e šâxe-ye qulhâ-ye sorx

Fr.: méthode du haut de la branche des géantes   

A technique for deriving extragalactic distances which uses the → luminosity of the brightest → red giant branch stars in old → stellar populations as a "standard candle." For old (> 2-3 Gyr), metal-poor ([Fe/H] < -0.7) stellar populations, this luminosity is relatively well determined, and the → absolute magnitude of these stars in the I band is roughly constant (MI = -4.1 ± 0.1).

M.E. tip; from M.L.G. or M.Du. tip "utmost point, extremity" (cf. Ger. zipfel, a diminutive formation); → red giant; → branch; → method.

Raveš, → method; nok "tip;" šâxé, → branch; qulhâ-ye sorx plural of qul-e sorx, → red giant.

tip-tilt mirror
  آینه‌یِ کج-و-راست-گر   
âyene-ye kaj-o-râst-gar

Fr.: miroir inclinable   

A rapidly moving → mirror used in → adaptive optics to correct overall movements of the incoming → wavefront of light caused by → atmospheric turbulence. The simplest form of adaptive optics is tip-tilt correction, which corresponds to correction of the tilts of the wavefront in two dimensions. This is done by tipping and tilting the mirror rapidly in response to overall changes in position of a reference star. See also → deformable mirror.

From, tip noun from tip (v.) "to overturn, upset," from M.E. typen "to upset, overturn" + tilt noun from tilt (v.) "to cause to lean, incline, slope, or slant," → tilt; → mirror.

Âyené, → mirror; kaj "turned aside; crooked, bent" (cf. Skt. kubja- "hump-backed, crooked," Pali kujja- "bent," L. gibbus "hump, hunch," Lith. kupra "hump") + -o- "and" + râstright + -gar agent noun suffix → -or.

xasté (#)

Fr.: fatigué   

Exhausted of strength and energy.

Past participle of tire "to weary; become weary," M.E. tyren, O.E. teorian, of unknown origin.

Xasté "tired; hurt, wounded;" Mid.Pers. xastan, xad- "to injure, wound;" Av. vīxaδ- "to crush;" Proto-Iranian *xad- "to wound, hurt."

tired light
  نور ِ خسته   
nur-e xasté

Fr.: fatigue de la lumière   

The hypothesis that photons from distant objects lose energy during their intergalactic journey to us, thereby increasing in wavelength and becoming redshifted. This would provide an alternative to the → Big Bang model in accounting for the → redshifts of distant galaxies. However, there is no evidence for any such tired-light effect. First discussed by F. Zwicky (1929, Proceedings of the National Academy of Sciences, 15, 773).

tired; → light.

Tisserand's parameter
  پارامون ِ تیسران   
pârâmun-e Tisserand

Fr.: paramètre de Tisserand   

In celestial mechanics, a combination of orbital elements commonly used to distinguish between comets and asteroids. Objects whose Tisserand's parameter value is smaller than 3 are considered to be dynamically cometary, and those with a value larger than 3 asteroidal. Also called Tisserand's invariant.

Named after François Félix Tisserand (1845-1896), French astronomer, Director of the Paris Observatory (1892).

Titân (#)

Fr.: Titan   

The fifteenth of → Saturn's known satellites and the largest. It has a diameter of 5150 km and orbits Saturn at a mean distance of 1,221,830 km. It is the only moon known to have an atmosphere. Also called Saturn XV.

In Gk. mythology the Titans were a family of giants, the children of Uranus and Gaia, who sought to rule the heavens but were overthrown and supplanted by the family of Zeus.

Titâniyâ (#)

Fr.: Titania   

The fourteenth and largest of → Uranus's known satellites. It has a diameter of 1578 km and orbits its planet at a mean distance of 436,270 km. Titania was discovered by Herschel in 1787. Also called Uranus IV.

Titania is the Queen of the Fairies and wife of Oberon in Shakespeare's Midsummer-Night's Dream.

titan (#)

Fr.: titane   

A dark-gray or silvery, very hard, light metallic element, occurring combined in various minerals; symbol Ti. Atomic number 22; atomic weight 47.88; melting point 1,675°C; boiling point 3,260°C; specific gravity 4.54 at 20°C. It is used in metallurgy to remove oxygen and nitrogen from steel and to toughen it.

It was originally discovered by the English clergyman William Gregor in the mineral ilmenite (FeTiO3) in 1791. It was rediscovered in 1795 by the German chemist Martin Heinrich Klaproth, who called it titanium because it had no characteristic properties to use as a name; from Titan + -ium.

Titan, loan from Fr., as above.

titanium oxide, TiO
  اکسید ِ تیتان   
oksid-e titân

Fr.: oxide de titane   

A → diatomic molecule made up of → titanium and → oxygen atoms. See → TiO band.

titanium; → band.

<< < -ti tan Tay tem ten Ter the the the the thi thr tid tim Tit top tot tra tra tra tra tri Tri tru Tuc tur Tyc Typ > >>