An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < -ti Tam Tay tel ten Ter Tha the the the thi Tho thr tid tim tit top tot tra tra TRA tra tra tri tri tru Tul tur two Typ > >>

Number of Results: 587
top-down structure formation
  دیسش ِ ساختار از بالا به پایین   
diseš-e sâxtâr az bâlâ bé pâyin

Fr.: formation des structures du haut vers le bas   

A cosmological model of → structure formation in which larger structures, such as galaxy → superclusters or perhaps even the vast → filaments and → voids, form earlier and then they fragment into smaller structures such as individual galaxies. Opposite of → bottom-up structure formation.

top; → down; → structure; → formation.

top-heavy IMF
   IMF ِ بالا-سنگین   
IMF-e bâlâ-sangin


A star formation process in which → massive stars form more abundantly than that predicted by standard models, whereby the top end of the → initial mass function is significantly flatter than the canonical → Salpeter slope.

top; → heavy; → initial mass function.


Fr.: sujet, thème   

1) The subject of a discourse or of one of its parts.
2) The main and explicit subject matter of a literary work, often composed of several themes.

From L. topica, from Gk. topikos "pertaining to a common place, of a place," from topos "a place."

Bârak, from bâre "subject, matter, meaning," as in dar bare-ye "in the matter of; about," + nuance suffix -ak.

topocentric coordinates
  هماراهای ِ جا-مرکزی   
hamârâhâ-ye jâ-markazi

Fr.: coordonées topocentriques   

A coordinate system that uses the observer's location as its central reference point. Usually, the difference in the position of an object in the sky measured using topocentric and geocentric coordinates is very small because most celestial objects are so far away. However, for nearby objects this is not true. The Sun, for example, may appear displaced as much as eight arcseconds from its geocentric position, and the Moon by as much as one degree.

Topocentric, from topo- combining form of Gk. topos "place" + centric, from → center; → coordinate.

Hamârâhâ, → coordinate; jâ-markazi "topocentric," from "place" (from Mid.Pers. giyâg "place;" O.Pers. ā-vahana- "place, village;" Av. vah- "to dwell, stay," vanhaiti "he dwells, stays;" Skt. vásati "he dwells;" Gk. aesa (nukta) "to pass (the night);" Ossetic wat "room; bed; place;" Tokharian B wäs- "to stay, wait;" PIE base ues- "to stay, live, spend the night") + markazi, of, pertaining to markaz, → center.

  توپوشناختی، توپوشناسیک   
topošenâxti, topošenâsik

Fr.: topologique   

Of or relating to → topology.

topology; → -ic; → -al

topological defect
  آک ِ توپوشناختی، ~ توپوشناسیک   
âk-e topošenâxti, ~ topošenâsik

Fr.: défaut topologique   

In → cosmological models, a stable configuration of → matter formed when the → early Universe underwent → phase transitions during which fundamental symmetries were broken. There are a number of possible types of defects, such as domain walls, → cosmic strings, → magnetic monopoles, and → texture s. Same as → cosmic defect.

topological; → defect.

topological space
  فضای ِ توپوشناختی   
fazâ-ye topošenâxti

Fr.: espace topologique   

A set X together with a collection of open subsets T that satisfies the three following conditions: 1) The empty set Ø and X are in T. 2) The intersection of a finite number of sets in T is also in T. 3) The union of an arbitrary number of sets in T is also in T.

topological; → space.


Fr.: topologie   

The study of the properties of geometric figures that remain invariant under certain transformations, as bending or stretching. A circle is topologically equivalent to an ellipse (into which it can be deformed by stretching) and a sphere is equivalent to an ellipsoid.

From topo- combining form of Gk. topos "place" + → -logy.

Topošenâsi, from topo-, loan from Gk., as above, + šenâsi-logy.

âhir (#)

Fr.: torche   

A light to be carried in the hand, consisting of some combustible substance, as resinous wood, or of twisted flax or the like soaked with tallow or other flammable substance, ignited at the upper end (

M.E. torche, from O.Fr. torche "torch," originally "twisted thing," then "torch formed of twisted tow dipped in wax," probably from V.L. *torca, alteration of L.L. torqua, from torquere "to twist," → torque.

Âhir, from Kurd. âhir "torch," variant of âzar, → fire.

Torino scale
  مرپل ِ تورین   
marpel-e Turin

Fr.: échelle de Turin   

A scale used to assess the threat posed by the → impact of a → near-Earth object (NEO). It considers the impact energy as well as the probability of impact. It is designed to communicate to the public the risk associated with a NEO in more qualitative form than the → Palermo scale. The → impact hazard is expressed by a number between 0 and 10 depending on the probability that an impact will occur and the kinetic energy of the potential → impactor. The extent of damage ranges from inconsequential (0) to catastrophic (10). The scale is color-coded such that white = no consequence; green = meriting careful monitoring; yellow = meriting concern; orange = threatening events; red = impact is certain.

Named for Torino, because the scale was adopted by that city in Italy in 1999; → scale.

  پیچ-توف، توفان ِ پیچنده   
pic-tuf, tufân-e picandé

Fr.: tornade   

A mass of rotating air with high wind speeds at its center. It is produced in a very severe thunderstorm and appears as a funnel cloud extending from the base of a Cumulonimbus to the ground.

Tornado, metathesis from Sp tronada "thunderstorm," from tronar "to thunder," from L. tonare "to thunder," → thunder.

Pic-tuf, from pic present stem of picidan "to twist, entwine, coil" (Mid.Pers. pecidan "to twist, entwine") + tuf short for tufân, → storm.
Tufân-e picandé, from tufânstorm + picandé agant noun/adj. of picidan

cambarvâr (#)

Fr.: toroïde   

A surface of revolution obtained by rotating a closed plane curve about an axis parallel to the plane which does not intersect the curve. The simplest toroid is the → torus. The solid enclosed by such a surface.

From tor-, from → torus + → -oid.

toroidal magnetic field
  میدان ِ مغناتیسی ِ چنبروار   
meydân-e meqnâtisi-ye cambarvâr

Fr.: champ magnétique toroïdal   

A magnetic field which is generated in a → plasma inside a → toroid, as in a → tokamak, by the electric current which spirals around the toroid. Toroidal field has no radial component. → poloidal magnetic field.

toroid; → magnetic field.

gaštâvar (#)

Fr.: couple   

The tendency of a → force applied to an object to cause the object to → rotate about a given → axis or → point. Torque is the rotational analogue of or the turning effect of a force. It is equal to the product of the force and its distance from the reference axis. More specifically, if a force F acts on a single particle at a point P whose position with respect to the origin O of the inertial reference is given by the distance vector r, the torque T acting on the particle with respect to the origin O is defined as: T = r × F. Torque is a → vector quantity. Its magnitude is given by: rF sin θ, where θ is the angle between r and F; its direction is normal to the plane formed by r and F. The sense is given by the → right-hand screw rule for the → vector product of two vectors. Torque has the same dimensions as work, but work is a scalar.

From L. torquere "to twist;" cf. Skt. tarku- "spindle;" maybe Mod.Pers. duk "spindle;" Mid.Pers. dôk "spindle;" O.C.S. traku "band, girdle," O.H.G. drahsil "turner," Ger. drechseln "to turn on a lathe;" O.E. thweorh "transverse, perverse, angry, cross;" E. thwart; PIE base *twork-/*twerk- "twist"

Gaštâvar literally "that which makes turn, turning agent," from gašt "turning," past stem of gaštan, gardidan "to turn, to change" (Mid.Pers. vartitan; Av. varət- "to turn, revolve;" 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") + âvar agent noun of âvardan "to bring; to cause, produce" (Mid.Pers. âwurtan, âvaritan; Av. ābar- "to bring; to possess," from prefix ā- + Av./O.Pers. bar- "to bear, carry," bareθre "to bear (infinitive)," bareθri "a female that bears (children), a mother;" Mod.Pers. bordan "to carry;" Skt. bharati "he carries;" Gk. pherein; L. fero "to carry").

torr (#)

Fr.: torr   

A unit of pressure used in the field of high vacuum, equivalent to 1 mm of mercury

After the Italian scientist Evangelista Torricelli (1608-1647), who invented the first barometer.

lâhez (#)

Fr.: torrent   

A stream of water flowing with great rapidity and violence. See also → rapids.

M.E., from M.Fr. torrent, from L. torrentem (nominative torrens) "a rushing (stream)," from torrere, "to parch, dry up, roast," → torrid.

Lâhez, from Tabari lahez "an overwhelming flow," Baxtiyâri lâhiz "flood." The first component lâh, lah maybe related to lur, Lori, Kordi laf, Tabari "flood," → cataclysm.

Torricelli's law
  قانون ِ توریچلی   
qânun-e Torricelli

Fr.: loi de Torricelli   

In fluid dynamics, a theorem that relates the speed of fluid flowing out of an opening to the height of fluid above the opening: v = (2gh)1/2, where v is the exit velocity of the water, h is the height of the water column, and g is the acceleration due to gravity (9.81 m/s2). It was later shown to be a particular case of → Bernoulli's theorem.

After the Italian scientist Evangelista Torricelli (1608-1647), who found this relationship in 1643.

  تفسان، تفسا   
tafsân, tafsâ

Fr.: torride   

Subject to the weather that is hot and dry enough to scorch land.

From L. torridus "dried with heat, scorching hot," from torrere "to dry up, roast," related to terra "earth," literally "dry land;" from PIE base *ters- "to dry" (cf. Pers. tešné "thirsty;" Mid.Pers. tašnak "thirsty;" Av. taršu- "dry," taršna- "thirst;" Skt. trsta- "dry," tars- "to be thirsty;" Gk. teresesthai "to become or be dry;" Goth. þaursus "dry, barren," O.H.G. derren "to make dry," durst "thirst;" Ger. dürr "arid;" O.E. þurstig "thirsty").

Tafsân, tafsâ, from tafsidan "to become hot," variants tâftan, tâbidan "to shine;" Mid.Pers. tâftan "to heat, burn, shine;" taftan "to become hot;" Parthian t'b "to shine;" Av. tāp-, taf- "to warm up, heat," tafsat "became hot," tāpaiieiti "to create warmth;" cf. Skt. tap- "; to heat, be/become hot; to spoil, injure, damage; to suffer," tapati "burns;" L. tepere "to be warm," tepidus "warm;" PIE base *tep- "to be warm."

Torrid Zone
  زنار ِ تفسان   
zonnâr-e tafsân

Fr.: Zone torride   

The part of the Earth's surface between the tropics of Cancer and Capricorn

torrid; → zone.

cambar (#)

Fr.: tore   

A surface produced by the revolution of a conic section (such as a circle) around a line lying in its plane, but not cutting the conic. The solid enclosed by such a surface.

From L. torus "a round, swelling protuberance."

Cambar "torus," originally "hoop, circle," from Mid.Pers. cambar "hoop; a ring-shaped headdress," cambar vâcik "playing tambourine."

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