abar-now-axtar-e rombeš-e maqzé
Fr.: supernova à effondrement de coeur
delayed supernova explosion
oskaft-e bâderang-e abar-now-axtar
Fr.: explosion retardée de supernova
A mechanism predicted by theoretical models of → supernova explosion that operates after the → supernova shock fails to deliver a → prompt supernova explosion. The delayed supernova explosion mechanism assumes that a few tenth of a second after the → iron core collapse, the supernova shock is stalled due to energy dissipation. The material between the → protoneutron star and the stalled shock is mainly disintegrated into neutrons and protons due to the high temperatures (a few MeV) in this region. As the → neutrinos coming from the protoneutron star run through this material, a fraction of the neutrinos are captured by the → nucleons, and their energy is deposited in the material. As a result, the material behind the shock is heated by the neutrinos. If this neutrino heating is efficient enough, the stalled shock can be reinvigorated to bring about a supernova explosion.
abar-now-axtar-e târixi (#)
Fr.: supernova historique
A supernova event recorded in the course of history before the invention of the telescope. The well recorded supernovae of this small group are SN 185, SN 1006, SN 1054 (→ Crab Nebula), SN 1181, SN 1572 (→ Tycho's star), and SN 1604 (→ Kepler's star).
abar-now-axtar-e nâpâydâri-ye joft
Fr.: supernova à instabilité de paires
A special type of → supernova that would result from the → pair instability in → supermassive stars with a mass range between 140 and 260 Msun in a low → metallicity environment. Such objects descended from the → Population III stars in the early history of the Universe. Such supernovae are the most powerful thermonuclear explosions in the Universe. Pair-instability supernovae may have played an important role in the synthesis of → heavy elements. Moreover, the energetic feedback of the processed elements to their surroundings could have affected the structure and evolution of the early Universe (See, e.g., Fryer et al. 2001, ApJ 550, 372; Heger & Woosley 2002, ApJ 567, 532). See also → pulsational pair-instability supernova.
prompt supernova explosion
oskaft-e tond-e abar-now-axtar, ~ biderang-e ~
Fr.: explosion rapide de supernova
A mechanism predicted by theoretical models of → supernova explosion in the case when the → supernova shock breaks through the outer edge of the collapsing → iron core before losing all of its energy (through → photodisintegration of the iron nuclei) and manages to expel the stellar envelope. Compare with → delayed supernova explosion.
pulsational pair-instability supernova
abar-now-axtar-e nâpâydâri-ye tapeši-ye joft
Fr.: supernova à instabilité pulsationnelle de paires
A → supernova resulting from the → pair instability that generates several successive explosions. According to models, a first pulse ejects many solar masses of hydrogen layers as a shell. After the first explosion, the remaining core contracts and searches for a stable burning state. When the next explosion occurs a few years later, several solar masses of material are again ejected, which collide with the earlier ejecta. This collision can radiate 1050 erg of light, about a factor of ten more than an ordinary → core-collapse supernova. After each pulse, the remaining core contracts, radiates neutrinos and light, and searches again for a stable burning state. Later ejections have lower mass, but have higher energy. They quickly catch up with the first shell, where the collision dissipates most of their kinetic energy as radiation. The first SNe from → Population III stars are likely due to pulsational pair instability (Woosley et al. 2007, Nature 450, 390). See also → pair-instability supernova.
Fr.: supernova superlumineuse
A → supernova with an → absolute magnitude of about -22 in optical. Examples of these newly discovered SNe include SN 2006gy, SN 2005ap, and SNe 2003ma. The nature of these objects is poorly known. Some of them are powered by the circumstellar interaction, or by the shock breakout from the dense circumstellar medium, as suggested by the presence of narrow emission lines in superluminous → Type II-N supernovae. It is also argued that superluminous SNe could be powered by a large amount of 56Ni which is synthesized as a result of energetic → core-collapse supernovae. Other scenarios include the interaction between shells ejected by the pulsational → pair-instability. See, e.g. Tanaka et al. 2012, MNRAS 422, 2675, arXiv:1202.3610, and references therein.
A violent stellar explosion which blows off all or most of the star's material at high velocity leaving a compact stellar remnant such as a neutron star or black hole. At maximum light, the supernova can have luminosity about 108 or 109 times that of the Sun. The phenomenon results from the later evolution of stars when an instability sets in the core following the nucleosynthesis of iron. In massive stars, the supernova occurs when the star has used up all its available nuclear fuel and it reaches a lower energy state through gravitational collapse to form a more compact star. In white dwarf stars in binary systems, accretion of mass onto the surface of a neutron star can be sufficient to take the star over the upper mass limit for stability as a white dwarf and it collapses to form a neutron star resulting in a → supernova explosion. See also → supernova types.
Fr.: candidat supernova
A star which according to observational data could become a supernova.
Fr.: éjecta de supernova
The material ejected by a → supernova explosion.
Fr.: énergie de supernova
Fr.: explosion de supernova
Fr.: rétroaction des supenovae
1) The process whereby the energy and matter contained in a → supernova
are injected into the → interstellar medium after the
→ supernova explosion.
The → thermal energy injected into the ISM serves to
→ suppress → star formation, while
→ heavy elements → nucleosynthesized
inside SNe tend to enhance star formation.
Fr.: supernova imposteuse
A brilliant burst of light that would suggest a → supernova explosion, but analysis of the star's → light curve, → spectrum, and → luminosity rules it out as a genuine supernova. Energetic → outbursts of → massive stars are often labeled as "supernova impostors" (Van Dyk et al. 2000). Many of these giant eruptions are spectroscopically similar to → Type II-n supernovae and thus receive a supernova (SN) designation, but are later recognized as subluminous or their spectra and light curves do not develop like true supernovae. Consequently, they are often referred to as "supernova impostors." These impostors or giant eruptions are examples of high → mass loss episodes apparently from evolved massive stars. Authors often refer to them as → Luminous Blue Variables (LBVs), but these giant eruptions are distinctly different from LBV/→ S Doradus variability in which the star does not increase in luminosity and the eruption or maximum light can last for several years. The mechanisms triggering these events are not yet fully understood (see, e.g., Humphreys et al., 2016, arXiv:1606.04959v1).
Fr.: progéniteur de supernova
A star which is at the origin of a supernova phenomenon.
supernova remnant (SNR)
Fr.: reste de supernova
The body of expanding gas ejected at a speed of about 10,000 km s-1 by a → supernova explosion, observed as a diffuse → gaseous nebula, often with a → shell-like structure. Supernova remnants are generally powerful → radio sources. The evolution of the SNR can be divided into different phases according to the dominant physical processes. Simplified models are made for the first stages, to get an idea of typical time scales, expansion velocities, and sizes. The three main phases are: 1) the → free expansion phase, 2) the → Sedov-Taylor phase, and 3) the → snowplow phase.
šok de abar-now-axtar, toš-e ~
Fr.: choc de supernova
A → shock wave that forms when the inner → iron core (of ~ 0.5 Msun) → collapses until it reaches densities in excess of → nuclear density. At this point the pressure rises dramatically and resists further collapse. The homologous core bounces and drives out a shock wave that works its way through the remainder of the initial iron core. The small compressibility of nuclear matter halts the infall of the innermost core by an elastic collective bounce whose kinetic energy is almost immediately depleted by the → photodisintegration of heavy nuclei and the emission of → neutrinos.
Fr.: types de supernova
The classification of supernovae according to the presence or absence of the absorption lines of different chemical elements that appear in their spectra shortly after their explosion. Basically, supernovae come in two main types: those that have hydrogen (Type II, from a very massive star that blows up) and those that do not (Type I, due to thermonuclear runaways in a less massive star). Both types exhibit a wide variety of subclasses. Type Ia lacks hydrogen and presents a singly-ionized silicon (Si II) line at 6150 Å, near peak light. Type Ib has non-ionized helium (He I) line at 5876 Å, and no strong silicon absorption feature near 6150 Å. Type Ic shows weak or no helium lines and no strong silicon absorption feature near 6150 Å. Type II stars also have various subclasses. See also → Type I supernova, → Type Ia supernova, → Type Ib supernova, → Type Ic supernova, → Type II supernova, → Type II-L supernova, → Type II-n supernova, and → Type II-P supernova
Fr.: supernova thermonucléaire
Same as → type Ia supernova
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.