abar-novâ-ye nâpâydâri-ye joft, abar-now-axtar-e ~ ~
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.
periodically variable supergiant (PVSG)
abarqul-e vartande-ye dowreyi
Fr.: supergÃ©ante variable pÃ©riodiquement
A variable → supergiant star with typical periods of the order of 10 to 100 days and amplitudes less than a few tenths of a magnitude. PVSGs are thought to be pulsating → g modes, caused by a density inversion, arising from an → opacity bump, most likely from Fe, H, and/or He.
Fr.: superamas de Persée-Poissons
A long, dense chain of galaxies with a length of almost 300 million → light-years, constituting one of the largest known structures in the → Universe. At the left end of the supercluster lies the massive → Perseus cluster (A426), one of the most massive clusters of galaxies within 500 million light-years.
platinum group element (PGE)
bonpâr-e goruh-e pelâtin
Fr.: élément du groupe du platine
One of the six metals → platinum (Pt), → iridium (Ir), → osmium (Os), → palladium (Pd), → rhenium (Rh), and → ruthenium (Ru) that are grouped together in the → periodic table. They are relatively hard and resistant to corrosion and are used in jewellery and in some industrial applications. All are resistant to chemical attack.
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-novâ-ye nâpâydâri-ye tapeši-ye joft, abar-now-axtar-e ~ ~ ~
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.
1) In the → eye, the apparently black opening in the center of the
→ iris that permits light to pass and be focused on the
From M.E. pupille, from O.Fr. pupille, from L. pupilla, originally "little girl-doll," diminutive of pupa "girl, doll" (Fr. poupée), so called from the tiny image one sees of himself reflected in the eye of another.
Mardomak "little man," the allusion being to the tiny image of himself reflected in the eye of another, from mardom "man, human being, mankind, people;" → people, + diminutive suffix -ak.
Fr.: masquage de pupille
A method for reaching the → diffraction-limited → angular resolution of a monolithic telescope by using an → interferometric technique. A mask with several small openings is placed in the telescope pupil plane or in a conjugated plane so as to only pass light from selected regions, thus transforming the telescope into an array of small subapertures without redundancy. When the light from each of these separate subapertures is combined, → interference fringes are formed which encode information on the spatial structure of the source (Haniff et al. 1987, Nature 328, 694). Coupled with a novel technique which filters the → atmospheric turbulence through fibers, pupil masking allows reaching a high dynamic range (Perrin et al. 2006, MNRAS 373, 747), which is necessary for detecting very faint objects, such as → exoplanets, adjacent to bright stars.
The Stern. One of the larger constellations of the southern hemisphere representing the stern of the ship Argo Navis, located at 7h 30m right ascension, 40Â° south declination. Its brightest star is → Naos. Abbreviation: Pup; genitive: Puppis.
From L. puppis "stern, poop, the rear, or aft part of a ship or boat."
Pasâl, from pas "behind" (e.g.: pas-e pardé
"behind the curtain"), variant pošt "back; the back;
behind" (Mid.Pers. pas "behind, before, after;"
O.Pers. pasā "after;" Av. pasca "behind (of space);
then, afterward (of time);" cf. Skt. paścā "behind,
after, later;" L. post, as above; O.C.S. po "behind,
after;" Lith. pas "at, by;" PIE *pos-, *posko-) +
-âl, → -al. → prow = farâl
Fr.: Puppis A
A → supernova remnant in the constellation → Puppis, and one of the brightest sources in the X-ray sky. The → supernova occurred about 4000 years ago at a distance of about 6,000 light-years. Also called SNR G260.4-03.4. Its X-ray designation is 2U 0821-42.
cahârtâ (#), cahârtâyi (#)
Fourfold; consisting of four parts.
M.E. from L. quadruplus, from quadru- + duple, from duplus, from du(o) "two" + -plus "fold."
Cahârtâ, from cahâr, → four, cognate with L. quattuor, + tâ "fold, plait, ply; piece, part" (Mid.Pers. tâg "piece, part").
Fr.: système quadruple
A stellar system consisting of four stars orbiting around a common → center of mass.
cahârqotbé (#), cahârqotbe-yi (#)
A set of either two → electric dipoles or two → magnetic dipoles in close proximity to each other arranged with alternating polarities and acting as a single unit. Quadrupole interactions are much smaller than dipole interactions, but can allow transitions forbidden in dipole moment transitions.
Fr.: anisotropie quadrupolaire
The → anisotropy which is at the origin of the → cosmic microwave background polarization. The quadrupole anisotropy could arise from three types of perturbations: → scalar perturbation, → vector perturbation, and → tensor perturbation
Fr.: lentille quadrupôle
Fr.: moment quadrupolaire
A quantity characterizing an electric charge distribution, determined by the product of the charge density, the second power of the distance from the origin, and a spherical harmonic over the charge distribution.
Fr.: amas du quintuplet
A bright → open cluster of stars located within 100 light-years of the center of the Milky Way Galaxy, and one of the three → Galactic center clusters. The Quintuplet cluster was originally noted for its five very bright stars, but it is now known to contain many luminous → massive stars that are not detected at visible wavelengths due to heavy extinction by dust along the line of sight. The cluster is about 4 million years old and had an initial mass over 104 solar masses. The five brighter stars of the cluster are dusty → WC Wolf-Rayet stars. The Quintuplet cluster also contains two → Luminous Blue Variables, the Pistol star and FMM362. The Pistol star has a luminosity 107 times solar making it one of the most luminous stars known. The Quintuplet cluster is more dispersed than the nearby → Arches cluster.
Quintuplet, from the five brightest stars originally observed; → cluster.
abarqul-e sorx (#)
Fr.: supergéante rouge
A supergiant star with spectral type K or M. Red supergiants are the largest stars in the Universe, but not necessarily the most massive. Betelgeuse and Antares are the best known examples of a red supergiant.
pâregi (#) , gosast (#)
From L. ruptura "the breaking (of an arm or leg), fracture," from p.p. of rumpere "to break."