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: 554
triple alpha process
  فراروند ِ آلفای ِ سه‌تایی   
farâravand-e âlfâ-ye setâyi

Fr.: réaction triple alpha   

A chain of nuclear fusion reactions by which three helium nuclei (→ alpha particles) are transformed into → carbon. First two nuclei of helium collide, fuse, and form a nucleus of → beryllium: 4He + 4He ↔ 8Be, which is unstable and will decay back into two helium nuclei within a few 10-17 seconds. However, due to sufficiently high density and temperature in the stellar core, during a third collision between beryllium and helium, carbon is formed: 8Be + 4He → 12C + γ. The triple-alpha process is possible owing to the existence of the → Hoyle state. It is the main source of energy production in → red giants and → red supergiants in which the core temperature has reached at least 100 million K. Also called → Salpeter process.

triple; → alpha particle; → process.

triple conjunction
  هم‌ایستان ِ سه‌تایی   
hamistân-e setâyi

Fr.: conjonction triple   

A rare event involving a particularly intricate set of movements of two planets or a planet and a star where they meet each other three times in a short period either in opposition or at the time of inferior conjunction, if an inferior planet is involved. The visible movement of the planet or the planets in the sky is therefore normally prograde at the first conjunction, retrograde at the second conjunction and again prograde at the third conjunction.

triple; → conjunction.

triple point
  نقطه‌ی ِ سه‌گانه   
noqte-ye segâné (#)

Fr.: point triple   

The definite pressure and temperature at which all three phases of a substance coexist in → phase equilibrium. The triple point of water has a pressure of 4.58 mm of Hg and a temperature of 273.16 °K.

triple; → point.

Noqté, → triple; segâné, from three + -gâné suffix forming plural entities, from Mid.Pers. -gânag, -gâna.

triple star
  ستاره‌ی ِ سه‌تایی   
setâre-ye setâyi

Fr.: étoile triple   

A group of three stars visually or physically associated with each other. → triple system.

triple; → star

triple system
  راژمان ِ سه‌تایی   
râžmân-e setâyi

Fr.: système triple   

A system of three stars which are physically associated among them.

triple; → system

triplet
  سه‌تایه   
setâyé

Fr.: triplet   

A group or set of three of one kind.
Optics: A compound lens made up of three elements that may or may not be cemented.

From trip-, from → triple + -et, from → doublet.

Setâyé, from setâ, → triple, + -(y)é nuance suffix.

triplet state
  حالت ِ سه‌تایه   
hâlat-e setâyé

Fr.: état triplet   

The electronic state of an atom or molecule which has two unpaired electrons, and therefore whose total spin angular momentum is equal to 1.

triplet; → state.

triquetrum
  سه‌شاخ، ذات‌الشعبتین   
se-šâx, zâtošša'bateyn

Fr.: triquetrum   

An ancient astronomical instrument first described by Ptolemy in the Almagest, used in measuring the altitude of a celestial body. It consisted of three long arms of wood. The first is perpendicular to the horizon; the second is connected at the head of the first with an axis. The third had a graduated scale. An object was sighted along one arm and its zenith distance was read on the graduated scale. It performed the same function as the quadrant. Also called parallactic ruler, Ptolemy's rule.

L. neuter of triquetrus "three corned," from tri-three + -quetrus "corned."

Se-šâx, literally "three corned," from three + šâx "horn, branch" (Mid.Pers šâk; cf. Skt. sakha- "a branch, a limb;" Arm. cax; Lith. šaka; O.S. soxa; PIE *kakhâ "branch").

tritium
  تریتیوم   
tritiom (#)

Fr.: tritium   

Unstable heavy → isotope of → hydrogen whose nucleus contains one → proton and two → neutrons. Tritium occurs naturally due to → cosmic rays interacting with atmospheric gases. In the most important reaction for natural tritium production, a fast neutron interacts with atmospheric nitrogen: 14N + n → 12C + 3T. Its → half-life is about 12 years. Tritium was formed in an intermediate step in light element synthesis in → early Universe.

N.L., from Gk. trit(os) "third" (from → tri- + -tos adj. suffix) + N.L. → -ium.

Triton
  تریتون   
Triton (#)

Fr.: Triton   

The seventh and the largest of → Neptune's satellites. It has a diameter of 2,700 km and orbits its planet at a mean distance of 354,760 km every 5.877 days. Triton was discovered by William Lassell in 1846 scarcely a month after Neptune was discovered. Triton is colder than any other measured object in the solar system with a surface temperature of -235° C. It has an extremely thin atmosphere. Nitrogen ice particles might form thin clouds a few kilometers above the surface. The atmospheric pressure at Triton's surface is about 15 microbars, 0.000015 times the sea-level surface pressure on Earth. Triton is the only large satellite in the solar system to circle a planet in a → retrograde motion, that is in a direction opposite to the rotation of the planet.

In Gk. mythology, Triton is a god of the sea, the son of Poseidon (Neptune); usually portrayed as having the head and trunk of a man and the tail of a fish.

trivial
  زب   
zab

Fr.: trivial   

1) Of very little importance or value; insignificant; commonplace; ordinary.
2a) Math.: A solution of an equation in which the value of every variable of the equation is equal to zero. For example, x2 + 2y2 = x + 3y has a trivial solution x = 0, y = 0.
2b) Of a theorem or proof: simple, transparent, or immediately evident.
Any theorem once a proof has been obtained, no matter how difficult the theorem was to prove in the beginning.
2c) For any natural number, the number itself and 1 which are called trivial divisors.
3) Chemistry: → trivial name.

From M.L. trivialis "found everywhere, commonplace; known by every body," from trivium literally "crossroad, a place where three roads meet," also "the lower division of the seven liberal arts taught in medieval universities, i.e. grammar, rhetoric, and logic," from tri-, → three, + via "road," since it was common in Roman Empire for three roads to meet.

Zab "easy, unbought, gratis; straight," variant zap, related to sabok "light, not heavy; unsteady;" Proto-Iranian *θrap-/tarp- "to be unsteady;" cf. Kurd. terpin "to stumble;" Pashto drabəl "to shake, press down;" Skt. trepa- "hasty;" Gk. trepein "to turn;" L. trepidus "agitated, anxious;" PIE *trep- "to shake, tremble."

trivial name
  نام ِ زب   
nâm-e zab

Fr.: nom trivial   

Chemistry: A common name for a chemical compound derived from the natural source, or of historic origin, and not according to the systematic nomenclature. For example, the trivial name of sodium chloride is → salt.

trivial; → name.

triviality
  زبی   
zabi

Fr.: trivialité   

The quality or state of being → trivial; something trivial.

trivial; → -ity;.

trivialize
  زبیدن، زب‌کردن   
zabidan, zab kardan

Fr.: trivialiser   

To make → trivial.

trivial; → -ize

Trojan asteroid
  سیارک ِ ترویایی   
sayyârak-e Troâ-yi

Fr.: astéroïde troyen   

A member of the family of asteroids that share → Jupiter's orbit and lie in elongated, curved regions around the two → Lagrangian points 60° ahead and behind of Jupiter. The Lagrangian points L4 and L5 host several thousands of them. Originally, the term Trojan applied only to asteroids sharing Jupiter's orbit; however, planetoidal bodies have been discovered at the Lagrangian points of Mars and Neptune as well, and are also referred to as → Mars Trojans and Neptune Trojans respectively.

M.E.; O.E. Troian, from Trojanus, from Troj(a) "Troy" + -anus; → asteroid.

Sayyârakhâ plural of sayyârak, → asteroid; Troâ-yi adj. of Troâ "Troy."

tropic
  هورگرد   
hurgard

Fr.: tropique   

Either of the two parallels of latitude on Earth at which the Sun appears overhead at the → summer and → winter solstices each year: → Tropic of Cancer, → Tropic of Capricorn . The tropics lie at latitudes 23°26', north and south, an angle defined by the Earth's → axial inclination.

M.E., from L. tropicus, from Gk. tropikos "of or pertaining to a turn or change; of or pertaining to to the turn of the Sun's apparent motion at solstice," from trope "a turning."

Hurgard, literally "Sun's turning," from hur, → Sun, + gard "turning, changing," from 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."

Tropic of Cancer
  هورگرد ِ خرچنگ   
Hurgard-e Xarcang

Fr.: Tropique du Cancer   

A parallel of latitude on the Earth, 23°26' north of the equator, where the Sun is directly overhead on the northern → summer solstice (around the 21st June each year), because the Sun reaches its most northerly declination. Some 3,000 years ago, this occurred when the Sun was in the → Zodiac constellation → Cancer, hence the name. However, → precession has resulted in a shift of the position of the Sun so that it is now in the constellation → Gemini on the summer solstice.

tropic; → Cancer.

Tropic of Capricorn
  هورگرد ِ وهیگ   
Hurgard-e Vahig

Fr.: Tropique du Capricorne   

A parallel of latitude on the Earth, 23°26' south of the equator, where the Sun is directly overhead on the southern → summer solstice (around the 21st December each year), because the Sun reaches its most southerly declination. Some 3,000 years ago, this occurred when Sun was in the → Zodiac constellation → Cancer, hence the name. However, → precession has resulted in a shift of the position of the Sun so that it is now in the constellation → Sagittarius on the northern → winter solstice.

tropic; → Capricorn.

tropical
  هورگردی   
hurgardi

Fr.: tropique   

1) Geography: Pertaining to, characteristic of, occurring in, or inhabiting the → tropics.
2) Astro.: A misnomer for → solar, as in → tropical year, or → vernal equinox, as in → tropical month.

tropic + → -al.

tropical month
  ماه ِ هموگانی   
mâh-e hamugâni

Fr.: mois tropique   

The average period of the revolution of the Moon about the Earth with respect to the → vernal equinox, a period of 27.321 582 days (27d 7h 43m 4.7s).

tropical; → month.

Mâh, → month; hamugâni, of or pertaining to hamugân, → equinox.

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