Fr.: équinoxe vrai
Fr.: horizon vrai
A large circle of the → celestial sphere whose plane is perpendicular to the radius of the Earth through the point. Same as → astronomical horizon. The → visible horizon usually lies lower than the true horizon. See also → dip of the horizon.
Fr.: nord vrai
The geographic north defined by the rotational pole of the Earth, as opposed to magnetic north defined by the geomagnetic north pole.
Fr.: position vraie
The coordinates of an object for a given date, with respect to the true equator and the true equinoxes for the instant of time in question.
true sidereal time
zamân-e axtari-ye râstin
Fr.: temps sidéral vrai
Fr.: Soleil vrai
Fr.: Trumpler 14
A young → massive star cluster in the → Carina Nebula, lying about 10 arcmin to the north-west of → Trumpler 16. It comprises several → O-type stars. In particular, its core contains at least three very early O-type stars; → HD 93129.
From a catalog by Robert J. Trumpler (1886-1956), the Swiss-American astronomer who studied the → open clusters at Lick Observatory (1930). He was the first to produce a definite evidence of the existence of → interstellar reddening, due to → absorption, and to estimate its magnitude.
Fr.: Trumpler 16
A → massive star, and the most populous cluster of the → Carina Nebula. It contains several → O-type stars and three known → Wolf-Rayet stars in addition to the famous → LBV star → Eta Carinae. Trumpler 16 is probably older than → Trumpler 14.
→ Trumpler 14.
To shorten by cutting off a part.
From L. truncatus "cut off," p.p. of truncare "to maim, cut off," from truncus "mutilated, cut off."
Kol kardan "to cut off the end of; to dock a tail," from kol "docked, short," variants in a large number of dialects: kola, kalta, kel, kelma, koc, kall, kor, kul in Gilaki, Tâleši, Lori, Malâyeri, Hamedâni, Qâeni, and others, cf. Av. kaurvô- "bald, docked," kaurvôduma- "with a bald tail," kaurvôgaoša- "with bald ears;" cf. Gk. kol(os) "docked" (kolouros "dock-tailed;" L. colurus) + kardan "to do, to make" (Mid.Pers. kardan, O.Pers./Av. kar- "to do, make, build," Av. kərənaoiti "makes," cf. Skt. kr- "to do, to make," krnoti "makes," karma "act, deed;" PIE base kwer- "to do, to make").
The act or process of truncating, as → disk truncation.
Verbal noun from → truncate.
1) The quality of being true, genuine, actual, or factual.
M.E. treuthe; O.E. trêowth "faith, faithfulness, fidelity; quality of being true," from triewe, treowe "faithful," → tue, with suffix *-itho-th.
Noun from râstin, → true, + noun suffix -i.
Fr.: fonction de vérité
Fr.: table de vérité
A table with columns and rows that lists the resultant → truth value of the given → sentences for each of the possible combinations of truth values to the simple sentences out of which the given sentences are constructed.
Fr.: valeur de vérité
The quality of a logical → proposition (or a formal → symbol) which describes the relation of a proposition to → truth. The traditional → formal logic admits only two contradictory values, → true or → false. In → symbolic logic, more specifically in → polyvalent logics, other truth values are used (such as possible, impossible, undetermined, probable, random, etc.).
A huge wave, caused by undersea earthquakes, volcanic eruptions, or, more rarely, by asteroid or meteoroid impact (as in the case of the K-T extinction).
From Japanese tsunami, from tsu "harbor" + nami "waves."
1) A long hollow cylinder of metal, glass, rubber, or other material used to transport or
contain liquids or gases.
M.E., from M.Fr. tube, from L. tubus "tube, pipe," of unknown origin.
Lulé "tube, pipe; roll," dialectal Lori, Laki lil, Laki lul "wanderer;" Hamadâni lul "spiral, coil."
tube of flow
Fr.: tube d'écoulement
Same as → flow tube.
tube of flux
Fr.: tube de flux
Bundles of lines of electrical intensity into which the vector field of electrical force can be divided. Same as tube of force, field tube.
The Toucan. A constellation of the southern hemisphere, at approximately 0h right ascension, -65° declination, represented as a toucan, a brightly colored South American bird with a very large, thick bill. Tucana contains the second most prominent → globular cluster in the sky, 47 Tucanae, and the → Small Magellanic Cloud. Abbreviation: Tuc; genitive: Tucanae. The constellation was one of twelve created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman Houtman between 1595 and 1597, and it first appeared in Johann Bayer's Uranometria of 1603.
From Fr., from Portugese tucano, from tucan (onomatopoeia) in the language spoken by the Tupi Indians in Brazil.
Fr.: relation Tully-Fisher
An observed correlation between the luminosity of a spiral galaxy and its rate of rotation (measured from its 21 cm hydrogen line). This means that more luminous galaxies have stars that are moving faster. Knowing the rotational velocity of a spiral galaxy, this relation provides its absolute magnitude and then its distance. → Faber-Jackson relation.
Named after R. B. Tully and J. R. Fisher who first derived this relationship (1977, A&A 54, 661); → relation.