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: 544
Tycho's star
  ستاره‌ی ِ توگو   
setâre-ye Tycho

Fr.: étoile de Tycho   

A → supernova of Type Ia in the constellation → Cassiopeia, which Tycho Brahe observed in November 1572. At its peak it was as bright as Venus and was visible in the daytime, reaching a magnitude of about -4. It is now visible as a → supernova remnant about 20 light-years across at a distance of about 7,500 light-years. It is associated with faint emission in the optical and X-rays, but is a strong radio source. Other designations: SN 1572, 3C 10, B Cas, 2U 0022+63.

Named after the Danish astronomer Tycho Brahe (1546-1601), who described the event; → star.

Tychonic model
  مدل ِ توگویی   
model-e Tychoyi

Fr.: modèle tychonique   

A hybrid of → geocentric and → heliocentric systems in which the Earth remains at the center, with the → Sun orbiting the Earth, but with all the other planets revolving about the Sun. Moreover, the fixed stars were located in a crystalline shell centered on the Earth.

Related to the Danish astronomer Tycho Brahe (1546-1601), who imagined the model; → model.

tympanum
  حجره   
hojré (#)

Fr.:tympan   

Thin brass disk inserted into the → mater of a → planispheric astrolabe. It carries the grid of → altazimuth coordinates shown in polar → stereographic projection for the → latitude of the specific observation locality. In addition to the main → vertical circles and the main → almucantars, the tympanum reproduces some elements of the → celestial sphere - the → celestial equator, the → tropic of Cancer, and the → tropic of Capricorn, as well as the hour lines for determining the unequal hours of day or night respectively from the Sun's position on the ecliptic or from the altitude of a star marked on the → rete (online museo galileo, VirtualMuseum).

From L. tympanum "drum," from Gk. tympanon "a drum, panel of a door," from root of typtein "to beat, strike."

Hojré, from Ar. hujrah "chamber."

Tyndall effect
  اسکر ِ تیندال   
oskar-e Tyndall

Fr.: effet Tyndall   

The observation whereby when light passes through a clear fluid holding small particles in suspension, the shorter blue wavelengths are scattered more strongly than the red. The effect is most commonly known as the → Rayleigh scattering.

Names for John Tyndall (1820-1893), who discovered the effect in 1859.

type
  گونه   
guné (#)

Fr.: type   

A group of items that have strongly marked and readily defined similarities.

M.E., from M.Fr., from L. typus "figure, image, form, kind," from Gk. typos "dent, impression, mark, figure, original form," from root of typtein "to strike, beat."

Guné "species; color; form; manner, kind;" Mid.Pers. gônak "kind, species;" Av. gaona- "color; body hair;" PIE base *góur- "(animal) body hair," genitive form *gunós.

Type 1 Seyfert (Sy 1)
  کهکشان ِ سیفرت ِ گونه‌ی ِ ۱   
kahkešân-e Seyfert-e guné-ye 1

Fr.: galaxie Seyfer de type 1   

A type of → Seyfert galaxy showing both broad and narrow spectral emission lines. The widths of the broad lines indicates velocities around 1000 km s-1. Sy 1 galaxies are also very bright sources of UV and X-ray emission.

type; → one; → Seyfert galaxy.

Type 2 Seyfert (Sy 2)
  کهکشان ِ سیفرت ِ گونه‌ی ِ ۲   
kahkešân-e Seyfert-e guné-ye 2

Fr.: galaxie Seyfer de type 2   

A type of → Seyfert galaxy showing only narrow emission lines and weak UV and X-ray emissions but strong IR emission.

type; → two; → Seyfert galaxy.

Type I burst
  بلک ِ گونه‌ی ِ I   
belk-e gune-ye I

Fr.: sursaut de type I   

A burst of → X-rays observed toward → low-mass X-ray binary (LMXB)s. It is characterized by a sharp increase in → luminosity, which lasts 1-10 s, followed by the peak and a slow decrease, which can last from ~ 10s to 100s. Observationally, X-ray bursts manifest as a bright peak of emission on top of the persistent emission powered by → accretion. See also → Type II burst.

type; → burst.

Type I error
  ایرنگ ِ گونه‌ی ِ I   
irang-e gune-ye I

Fr.: erreur de type I   

Statistics: An error made if a → hypothesis is rejected when it should be accepted. → Type II error.

type; → error.

Type I migration
  کوچ ِ گونه‌ی ِ I   
kuc-e gune-ye I

Fr.: migration de type I   

An → orbital migration of low-mass → planets in which no gap is created in the → protoplanetary disk. According to planetary models, beyond a critical core mass for the forming planet, a gap in the protoplanetary disk is created. The critical mass depends on the mass and → metallicity of the disk and therefore it does not have a singular value, but has been shown to be between about 10-30 Earth masses. Compare with → Type II migration.

type; → migration.

Type I supernova
  ابر-نو-اختر ِ گونه‌ی ِ I   
abar-now-axtar-e gune-ye I

Fr.: supernova de type I   

A type of supernova whose spectra lacks hydrogen lines. Its → light curve exhibits a sharp maximum with a gradual decrease. Typical magnitudes MV = -14 to -17. Ejecta velocities about 10,000 km/sec. Type I supernovae have several subtypes: → Type Ia, → Type Ib, and → Type Ic.

Type I initially introduced by R. Minkowski (1941, PASP 53, 224); → type; → supernova.

Type I tail
  دم ِ گونه‌ی ِ I   
dom-e gune-ye I

Fr.: queue de type I   

The → gas tail of of a comet.

type; → tail.

Type Ia supernova
  ابر-نو-اختر ِ گونه‌ی ِ Ia   
abar-now-axtar-e gune-ye Ia

Fr.: supernova de type Ia   

A → Type I supernova that presents a singly-ionized silicon (Si II) absorption feature at 6150 Å near peak brightness. Type Ia SNe are believed to result from mass → accretion to a carbon-oxygen → white dwarf in a → close binary system. When the white dwarf mass exceeds the → Chandrasekhar limit, the → degenerate electron pressure can no longer support the accumulated mass and the star collapses in a thermonuclear explosion producing a supernova. The → peak luminosity of SNe Ia is set by the radioactive decay chain 56Ni → 56Co → 56Fe, and the observed photometric correlation between the peak luminosity and the time-scale over which the → light curve decays from its maximum is understood physically as having both the luminosity and → opacity being set by the mass of 56Ni synthesized in the explosion. Type Ia supernovae occur in all types of galaxies. Type Ia SNe are used as → standard candles in determining cosmological distances, after normalizing their light curves with the → Phillips relation.

type; → supernova.

Type Ib supernova
  ابر-نو-اختر ِ گونه‌ی ِ Ib   
abar-now-axtar-e gune-ye Ib

Fr.: supernova de type Ia   

A → Type I supernova that has neutral helium line (He I) at 5876 Å, and no strong silicon (Si II) absorption feature at 6150 Å. Type Ib supernovae are believed to result from the evolution of → massive stars.

type; → supernova.

Type Ic supernova
  ابر-نو-اختر ِ گونه‌ی ِ Ic   
abar-now-axtar-e gune-ye Ic

Fr.: supernova de type Ia   

A → Type I supernova that shows weak or no helium lines and no strong silicon (Si II) absorption feature near 6150 Å. Type Ic supernovae are believed to result from the evolution of → massive stars.

type; → supernova.

Type II burst
  بلک ِ گونه‌ی ِ II   
belk-e gune-ye II

Fr.: sursaut de type II   

A burst of → X-rays observed toward → low-mass X-ray binary (LMXB)s and characterized by quick succession of bursts with recurrence intervals as short as ~ 7 s. Type II X-ray bursts look similar to → Type I bursts, but they are thought to be related with spasmodic episodes of → accretion.

type; → burst.

Type II error
  ایرنگ ِ گونه‌ی ِ II   
irang-e gune-ye II

Fr.: erreur de type II   

Statistics: An error made if a → hypothesis is accepted when it should be rejected. → Type I error.

type; → error.

Type II migration
  کوچ ِ گونه‌ی ِ II   
kuc-e gune-ye II

Fr.: migration de type II   

The → orbital migration of forming → planets that → accrete enough disk material to exceed the critical mass. This type migrates in a gap created in the → protoplanetary disk. Compare with → Type I migration.

type; → migration.

Type II supernova
  ابر-نو-اختر ِ گونه‌ی ِ II   
abar-now-axtar-e gune-ye II

Fr.: supernova de type II   

A supernova type whose spectrum contains hydrogen lines. Compared with → Type I supernovae, its → light curve has a broader peak at maximum and dies away more rapidly. The magnitudes are smaller, ranging from MV = -12 to -13.5, and the ejecta have lower velocities (about 5,000 km/sec). These supernovae, which result from the final evolution of → massive stars, have three main divisions: → Type II-P, → Type II-L, and → Type II-n.

Type II initially introduced by R. Minkowski (1941, PASP 53, 224); → type; → supernova.

Type II tail
  دم ِ گونه‌ی ِ II   
dom-e gune-ye II

Fr.: queue de type II   

The → dust tail of a → comet.

type; → tail.

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