tidal disruption event (TDE)
ruydâd-e gosixt-e kešandi
Fr.: événement de rupture par effet de marée
The process in which a star is torn apart by the → tidal forces of a → supermassive black hole. About 50% of the star's mass is eventually → accreted by the → black hole, generating a flare, which, in extreme cases of very high (→ super-Eddington) mass → accretion rates, can result in a → relativistic jet. TDEs have been proposed as sources of → ultra-high-energy cosmic rays and suggested as sources of high energy astrophysical → neutrinos (W. Winter and C. Lunardini, 2021, Nature Astronomy, arXiv:2005.06097 and references therein).
tidal disruption flare
âlâv-e gosixt-e kešandi
A luminosity enhancement in the → light curve of a galaxy observed in X-rays or ultraviolet surveys supposed to be associated with the → tidal disruption of a star that has passed close to a → supermassive black hole in the core of a → host galaxy. An → accretion disk forms after the tidal disruption. The flare event marks the beginning of the accretion process onto the black hole.
joft-e Tusi (#)
Fr.: couple de Tusi
Named for Nasireddin Tusi (1201-1274), director of Marâgha observatory who created the Ilkhani zij; → couple.
Type I supernova
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 Ia supernova
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 Ib supernova
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 Ic supernova
abar-now-axtar-e gune-ye Ic
Fr.: supernova de type Ia
Type II supernova
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-L supernova (SN II-L)
abar-now-axtar-e gune-ye II-L
Fr.: supernova de type II-L
Type II-n supernova (SN II-n)
abar-now-axtar-e gune-ye II-n
Fr.: supernova de type II-n
Type II-P supernova (SN II-P)
abar-now-axtar-e gune-ye II-P
Fr.: supernova de type II-P
A → Type II supernova which reaches a plateau in its → light curve. The vast majority of Type II SNe are characterized by a fast (few days) rise to a flat light curve, most pronounced in the reddest optical bands, with a duration of 80-100 days. This plateau phase is interpreted as the recession of the photosphere as the ejecta expand and cool. The spectra of SNe II-P are typically dominated by strong → P Cygni profiles of hydrogen lines, as well as iron absorption features (for a review, e.g., see Filippenko 1997, ARA&A 35, 309).
goruh-e yekâyi, ~ yekâni
Fr.: groupe unitaire
The set of n × n unitary matrices (→ unitary matrix).
Fr.: en haut
To, toward, or in a more elevated position.
M.E. up(pe) (adv.), O.E. up(p) "to a higher position;" cf. O.Frisian up, O.S. up, M.Du. up, op, O.N. upp; O.H.G. uf; (Ger. auf), Goth. iup.
Bâlâ "up, above, high, elevated, height" (related to boland "high," borz "height, magnitude" (it occurs also in the name of the mountain chain Alborz), Lori dialect berg "hill, mountain;" Mid.Pers. buland "high;" O.Pers. baršan- "height;" Av. barəz- "high, mount," barezan- "height;" cf. Skt. bhrant- "high;" L. fortis "strong" (Fr. & E. force); O.E. burg, burh "castle, fortified place;" Ger. Burg "castle;" Goth. baurgs "city;" E. burg, borough; Fr. bourgeois, bourgeoisie, faubourg); PIE base *bhergh- "high."
1) farâz-padâk; 2) farâz-padâkidan
Fr.: 1) rampe, montée; 2) promouvoir, revaloriser
1a) An incline going up in the direction of movement.
The process by which an area of Earth's crust slowly rises either due to increasing upward force applied from below or decreasing downward force (weight) from above.
1) bârgozâštan; 2) bârgozâri (#)
Fr.: 1) mettre en ligne; 2) mise en ligne
bâlâ (#), zabarin (#)
Higher, as in place, position, pitch, or in a scale.
Fr.: haut du bras
Bâzu "arm," from Mid.Pers. bâzûk "arm;" Av. bāzu- "arm;" Mod.Pers. bâhu "stick, staff; arm;" cf. Skt. bāhu- "arm, forearm;" Gk. pechys "forearm, arm, ell;" O.H.G. buog "shoulder;" Ger. Bug "shoulder;" Du. boeg; O.E. bôg, bôh "shoulder, bough;" E. bough " a branch of a tree;" PIE *bhaghu- "arm").
havâsepehr-e zabarin, javv-e ~
Fr.: atmosphère supérieure
The general term applied to the atmosphere above the → troposphere.
Fr.: culmination supérieure
Same as → superior culmination.