AGB final thermal pulse (AFTP)
tape-ye garmâyi-ye pâyâni-ye AGB
Fr.: flash de l'hélium final de l'AGB
In evolutionary models of → low-mass and → intermediate-mass stars, the occurrence of a → helium shell flash just at the moment when the star is leaving the → asymptotic giant branch phase.
A situation in which two heavenly bodies apparently approach each other. A close → conjunction in which no → occultation actually occurs.
L. appulsus, from appellere, appulsum "to drive to," from ad, → ad- + pellere "to drive".
Hamtâxt from ham- "against; together" + tâxt, from tâxtan "to rush upon, run, assault".
Of a force acting on a body, the → product of the → force and the → time for which it acts. If the force changes with time, the impulse is the → integral of the force with respect to the time during which the force acts, and is equal to the total change of → momentum produced by the force: ∫F dt = ∫m dv. Impulse is a → vector quantity.
From L. impulsus "a push against, pressure, shock," p.p. of impellere "to push, strike against, drive forward," from → in- "into" + pellere "to push, drive."
Tekâné, from tekân "involuntary motion, sudden shaking," related to tak "rush, quick motion, stroke, blow" (tâxtan, tâzidan "to run; to hasten; to assault"); Mid.Pers. tak "assault, attack;" Av. taka- "leap, run," from tak- "to run, flow;" cf. Skt. tak- "to rush, to hurry," takti "runs;" O.Ir. tech- "to flow;" Lith. teketi "to walk, to flow;" O.C.S. tešti "to walk, to hurry;" Tokharian B cake "river;" PIE base *tekw- "to run; to flow;" → flow.
Fr.: principe impulsion-quantité de mouvement
The vector → impulse of the → resultant force on a particle, in any time interval, is equal in magnitude and duration to the vector change in momentum of the particle: ∫F dt = mv2 - mv1. The impulse-momentum principle finds its chief application in connection with forces of short duration, such as those arising in collisions or explosions. Such forces are called → impulsive forces.
late thermal pulse
tape-ye garmâyi-ye dirân
Fr.: flash de l'hélium tardif
In evolutionary models of → low-mass and → intermediate-mass stars, the occurrence of a → helium shell flash on the → horizontal branch of the → post-AGB track, while → hydrogen shell burning is still going on.
Fr.: pulse précurseur
A component of a → pulsar pulse that appears shortly in advance of the main pulse.
1) tapidan (#); 2) tap, tapeš (#)
Fr.: 1) battre, vibrer, pulser; 2) impulsion
1a) (v.) To → beat, to → vibrate.
M.E., from M.Fr. pous, from L. pulsus "a beat," p.p. of pellere "to push, drive," from PIE *pel- "to shake, swing."
Tapidan "to beat, throb," Mid.Pers. tapīdan "to be anguished; to suffer; to grow hot, to be hot," variant tâftan, tâpidan "to stir up, to excite; to shine;" tâp "fever;" Av. tap- "to be hot, to grow hot," tafnah-, tafnu- "fever, feverish heat;" cf. Skt. tap- "to spoil, injure, damage,; to suffer; to give out heat, to be hot," tápati; L. tepere "to be warm;" PIE base *tep- "warm."
Fr.: compteur d'impulsion
A device that records counts the total number of pulses received over a given time interval.
Fr.: arrÃªt de pulsation
A phenomenon seen in the → radio → emission of many → pulsars where the emission appears to cease, or is greatly diminished, for a certain number of pulse periods. Typical time scales of nulling are of the order of a few pulse periods, however it may last for up to many hours in certain pulsars. For example, PSR B0826-34 is active for only about 20% of the time. Same as → pulsar nulling.
Fr.: largeur de pulsation
The interval of time between two successive pulses. Also called pulse length, pulse duration.
Fr.: laser pulsé
A laser that emits short pulses of coherent light in fixed intervals, rather than a continuous flow of photons. → laser; → high power laser.
To drive back; to repel.
M.E., from L. repulsus, p.p. of repellere, from → re- "back" + pellere "to drive, strike, push."
Vâzadan "to repulse," from vâ-→ re- + zadan "to strike, beat; to play an instrument; to do" (Mid.Pers. zatan, žatan; O.Pers./Av. jan-, gan- "to strike, hit, smite, kill" (jantar- "smiter"); cf. Skt. han- "to strike, beat" (hantar- "smiter, killer"); Gk. theinein "to strike;" L. fendere "to strike, push;" Gmc. *gundjo "war, battle;" PIE *gwhen- "to strike, kill").
tape-ye garmâyi, tapeš-e ~
Fr.: pulsation thermique
Repeated instabilities of the He burning shell which ignites in sudden burst during the final phases of the → AGB evolution.
very late thermal pulse (VLTP)
tape-ye garmâyi-ye besyâr dir
Fr.: flash de l'hélium très tardif
In evolutionary models of → post-asymptotic giant branch stars, the occurrence of the helium shell burning when the star has reached the → white dwarf cooling track. This leads to the possibility of a violent → helium shell flash and expansion on a time-scale of ≤ 10 years. The rapid expansion and prompt change in surface composition observed in → Sakurai's Object are thought to be due to such a very late thermal pulse.