haft xâharân, camce-ye kucak
Fr.: Petite Ourse
Same as → Little Dipper.
Fr.: période sothique
The interval after which the heliacal rising of the star Sirius occurs at the same time of the year. It is a period of 1,460 Sothic years.
From Fr. sothique, from Gk. Sothis, an Egyptian name of Sirius; → period.
Fr.: dispersion spectrale
Fr.: température de spin
standard temperature and pressure (STP)
damâ o fešâr-e estândé
Fr.: conditions normales de température et de pression
1) The most commonly used definition is temperature of 273.15 K (0 °C) and
pressure of 1 → atmosphere.
âzmâyeš-e Stern-Gerlach (#)
Fr.: expérience de Stern et Gerlach
An experiment devised for measuring the → magnetic moment of → silver atoms. A → beam of silver atoms is directed between the → poles of a non-homogeneous → magnetic field. Contrarily to the prediction of the classical theory, the atoms divide into two distinct parts. One half of atoms are deflected up, the other half deflected down. The amount of deflection up or down is exactly of the same magnitude. Whether an individual atom is deflected up or down appears to be random. From a measurement of the → deflection, one can find the strength of the magnetic moment. This experience provides proof that there exist only two permitted orientations, called the → quantization of → spin.
In honor of Otto Stern (1888-1969), German physicist, Nobel laureate in Physics 1943, and Walter Gerlach (1889-1979), German physicist, who carried out the experiment in 1922. They used a beam of silver atoms from a hot oven because they could be readily detected on a photograph emulsion. Moreover, the silver atoms allowed studying the magnetic properties of a single electron because the atoms have a single outer electron; → experiment.
Fr.: pleine lune de périgée
Same as → perigee full Moon.
super star cluster (SSC)
Fr.: super amas stellaire
A group of hundreds to thousands of very young stars packed into an unbelievably small volume of a few parsecs in size. These objects represent the youngest stage of → massive star cluster evolution yet observed. The most massive and dense SSCs, with ages less than 106 years, may be proto globular clusters. SSCs are thought to dissolve within 10 million years and merge into the field star population.
A prefix occurring originally in loanwords from Latin, with the basic meaning "above, beyond."
L. adverb and preposition super "above, over, on the top (of), beyond, besides, in addition to," from PIE base *uper "over," cognate with Pers. abar-, as below.
Mid.Pers. abar (Mod.Pers. bar- "on, upon, up"); O.Pers. upariy "above; over, upon, according to;" Av. upairi "above, over," upairi.zəma- "located above the earth;" cf. Gk. hyper- "over, above;" L. super-, as above; O.H.G. ubir "over."
Fr.: étoile super-canonique
super-Chandrasekhar SN Ia
abar-now-axtar-e gune-ye Ia-ye abar-Chandrasekhar
Fr.: supernova de type Ia super-Chandrasekhar
A superluminous → Type Ia supernova which is characterized by a bright → light curve peak, a slow light curve evolution during the photospheric phase, and moderately low ejecta velocities. Modeling suggests ejecta masses far in excess of the → Chandrasekhar limit of mass for non-rotating → white dwarfs and the production of about 1.5 Msun of 56Ni. This precludes the interpretation of these events as thermonuclear explosions of Chandrasekhar-mass white dwarfs.
An → extrasolar planet more massive than the Earth but less massive than 10 → Earth masses. The first discovered super-Earth orbits an M4 V star named GJ 876. Its estimated mass is 7.5±0.7 Earth masses and it has an orbital period of 1.94 days. It is close to the host star, and the surface temperature is calculated to lie between 430 and 650 K (Rivera et al. 2005, ApJ 634, 625).
Fr.: vent super-Eddington
Fr.: étoile très riche en métaux
superadiabatic temperature gradient
zine-ye damâ-ye abar-bidarrow
Fr.: gradient de température super-adiabatique
A condition in which there is an excess of the actual temperature gradient over the → adiabatic temperature gradient corresponding to the same pressure gradient. A region with superadiabatic temperature gradient is convectively unstable. → Hayashi forbidden zone.
A cavity hundreds of light-years across filled with a hot gas blown into the interstellar medium by multiple supernovae and stellar winds. Examples are the Local Bubble in the Orion Arm of the Milky Way and the N44 Superbubble in the Large Magellanic Cloud.
1) An aggregation of clusters of galaxies (→ galaxy cluster).
Superclusters are typically about one hundred million (108)
→ light-years in diameter and
contain tens of thousands of galaxies. Some examples are the
→ Local Supercluster,
→ Centaurus supercluster,
→ Laniakea supercluster,
→ Perseus-Pisces supercluster→ Shapley supercluster→ Virgo supercluster.
Grouping of galaxies in supercluster structure.
The phenomenon in which certain materials, when cooled to a sufficiently low temperature, lose all resistance to the flow of electricity.
A material which shows almost perfect conductivity at temperatures approaching absolute zero.