An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1290
standard model of particle physics
  مدل ِ استانده‌ی ِ فیزیک ِ ذره‌ای   
model-e estânde-ye fizik-e zarre-yi

Fr.: modèle standard de la physique des particules   

The theory developed since the 1970s, which is based on the theories and discoveries since the 1930s, and aims at explaining the fundamental structure of matter. According to the standard model, everything in the universe is made from a few basic building blocks called fundamental particles, governed by four fundamental forces. The particles occur in two basic types, called quarks and leptons. Three of the four fundamental forces (except gravity) and their carrier particles are included in the Standard Model. The Standard Model has successfully explained almost all experimental results and precisely predicted a wide variety of phenomena. Over time and through many experiments, the Standard Model has become established as a well-tested physics theory.

standard; → model; → particle; → physics.

standard stars
  ستارگان ِ استانده   
setâregân-e estândé

Fr.: étoiles standard   

Stars for which accurate color indices and/or magnitudes exist, defining a standard system.

standard; → star.

standard system
  راژمان ِ استانده   
râžmân-e estândé

Fr.: système standard   

Photometric system used as a reference.

standard; → system.

standard temperature and pressure (STP)
  دما و فشار ِ استانده   
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.
2) Chemistry: Temperature of 273.15 K (0 °C) and pressure of 105  → pascal (Pa)s (1 → bar). International Union of Pure and Applied Chemistry (IUPAC) recommends that the former use of the pressure of 1 atm as standard pressure (equivalent to 1.01325 × 105 Pa) should be discontinued.

standard; → temperature; → pressure.

standard time
  زمان ِ استانده   
zamân-e estândé

Fr.: temps standard   

The time in any of the 24 internationally agreed time zones into which the Earth's surface is divided. The primary zone is centered on the Greenwich meridian (0° longitude).

standard; → time.

standard values
  ارزش‌های ِ استانده   
arzešhâ-ye estândé

Fr.: valeurs standard   

Photometric values of selected stars in a standard system.

standard; → value.

standing wave
  موج ِ ایستان   
mowj-e istân

Fr.: onde stationnaire   

A wave produced by the simultaneous transmission of two similar wave motions in opposite directions. Same as stationary wave.

Standing verbal adjective from stand, cognate with Pers. istâdan, as below; → wave.

Istân pr.p. of istâdan "to stand;" Mid.Pers. êstâtan; O.Pers./Av. sta- "to stand, stand still; set;" Av. hištaiti; cf. Skt. sthâ- "to stand;" Gk. histemi "put, place, weigh," stasis "a standing still;" L. stare "to stand;" Lith. statau "place;" O.N. standa, Goth. standan, O.H.G. stantan, Swed. stå, Du. staan, Ger. stehen; O.E. standan; PIE base *sta- "to stand;" mowj, → wave.

setâré (#)

Fr.: étoile   

A huge mass of hot gas whose radiation is provided by its internal → thermonuclear reactions. A star represents a → hydrodynamic equilibrium between two opposing forces, the inward → gravitational force, which is attempting to make the mass collapse and the pressure caused by the generation of nuclear energy. Below a certain mass (0.08 → solar masses), the central pressures and temperatures are insufficient to trigger the → hydrogen fusion (→ brown dwarf). Stars have a variety of masses and sizes. → Massive stars are less common than → low-mass stars (→ initial mass function). → Star formation results from → gravitational collapse of → molecular clouds (→ fragmentation; → pre-stellar core; → protostar; → accretion). After leaving the → main sequence, they pass through several evolutionary stages (e.g., → red giant, → supergiant, → white dwarf, → supernova, → neutron star) depending on their initial masses. See also: → internal structure of stars; → spectral classification; → luminosity class; → variable star; → multiple star. The term star is sometimes loosely applied to objects that do not comply with the above specifications, but are evolutionary products of stars, such as neutron stars and white dwarfs. For ancient civilizations a star was anything appearing in the night sky, apart from perhaps the Moon.

M.E. sterre, O.E. steorra; cf. O.S. sterro, O.N. stjarna, O.Fris. stera, Du. ster, O.H.G. sterro, Ger. Stern, Goth. stairno; cognate with Gk. aster, astron, L. stella (Fr. étoile, Sp. esterella, It. stella), Bret. sterenn, Pers. setâré, as below.

Setâré, variants star, estâr, estâré, and probably axtar, → astro-, (Lori, Laki) âsâra, (Laki) hasâra, (Tabari) essâra, (Baluci) istâr, (Ossetic) st'aly, (i)sthalu, (Tâti) usdurâ; Mid.Pers. stârag, stâr; Av. star-; cf. Skt. stár-, tāra-, tārakā- "star;" akin to Gk. and L., as above; PIE base *ster- "star."

star catalog
  کاتالوگ ِ ستارگان   
kâtâlog-e setâregân

Fr.: catalogue stellaire   

A listing of stars usually ordered by right ascension with observational data elements such as coordinates, magnitude, distance, proper motion, and so on.

star; → catalog.

star chart
  نگاره‌ی ِ ستارگان   
negâre-ye setâregân

Fr.: carte du ciel   

A chart or map showing the relative apparent positions of the stars as viewed from the Earth.

star; chart, from M.Fr. charte "card, map," from L. charta "leaf of paper, tablet," from Gk. khartes "layer of papyrus."

Negâré, from negâr "picture, figure," from negâštanPictor; setâregân plural of setâréstar.

star cluster
  خوشه‌ی ِ ستاره‌ای   
xuše-ye setâre-yi (#)

Fr.: amas stellaire   

1) A group of stars held together by the mutual → gravitational attraction of its members, which are physically related through common origin. They are of two types: → open clusters and → globular clusters.
2) A → bound stellar agglomeration for which the age of the stars exceeds the → crossing time (Giels & Portegies Zwart, 2010, MNRAS Letters, astro-ph/1010.1720). See also → stellar association

star; → cluster.

star count
  شمارش ِ ستاره، ~ ستارگان   
šomâreš-e setâré, ~ setâregân

Fr.: comptage d'étoiles   

The number of stars that appear in a given region of sky, usually counted on a photographic plate or CCD image.

star; → count.

star drift
  دلک ِ ستارگان   
delek-e setâregân

Fr.: dérive stellaire   

The relative motion of two groups of stars in the Galaxy moving in opposite directions.

star; → drift.

star formation
  دیسش ِ ستاره   
diseš-e setâré

Fr.: formation d'étoiles   

The process by which dense parts of molecular clouds collapse into a ball of plasma to form a star. As a branch of astronomy, star formation includes the study of the interstellar medium and molecular clouds as precursors to the star formation process as well as the study of young stellar objects.

star; → formation.

star formation efficiency
  کارایی ِ دیسش ِ ستاره   
kârâyi-ye diseš-e setâré

Fr.: efficacité de formation d'étoiles   

The degree to which stars form in a system, such as a molecular cloud or a galaxy. It is given by the ratio of the total mass of stars to the initial gas mass.

star formation; → efficiency.

star formation history
  تاریخ ِ دیسش ِ ستاره   
târix-e diseš-e setâré

Fr.: histoire de formation d'étoiles   

The → star formation rate as a function of time.

star; → formation; → history.

star formation quenching
  اسرش ِ دیسش ِ ستارگان   
osereš-e diseš-e setâregân

Fr.: assèchement de formation d'étoiles   

The premature termination of star formation process in some galaxies. The ultimate quenching of star formation is caused by stripping of the gas reservoir which will finally turn into stars. A wide variety of mechanisms have been proposed to provide quenching. For example, → major mergers can transform spiral galaxies into ellipticals, and may also quench future star formation by ejecting the → interstellar medium from the galaxy via starburst, → active galactic nucleus, or shock-driven winds. In rich clusters, where merging is less efficient because of the large relative velocities of galaxies, rapid encounters or fly-bys may cause the formation of a bar and growth of a spheroidal component instead of larger scale star formation. Also, cold gas can be stripped out of the galaxy both by tidal forces and ram pressure in the intracluster medium. Similarly, the hot halo that provides future fuel for cooling and star formation may be efficiently stripped in dense environments, thus quenching further star formation (see, e.g., Kimm et al., 2009, MNRAS 394, 1131, arXiv:0810.2794).

star; → formation; → quench.

star formation rate
  نرخ ِ دیسش ِ ستاره   
nerx-e diseš-e setâré

Fr.: taux de formation d'étoiles   

The rate at which a molecular cloud or a galaxy is currently converting gas into stars. It is given by the ratio of the number of stars to the star formation time-scale.

star formation; → rate.

star formation region
  ناحیه‌ی ِ دیسش ِ ستاره   
nâhiye-ye diseš-e setâré

Fr.: région de formation d'étoiles   

A region in the → interstellar medium where processes of → star formation are going on or have occurred in the past.

star; → formation; → region.

star formation time scale
  مرپل ِ زمانی ِ دیسش ِ ستاره   
marpel-e zamâni-ye diseš-e setâre

Fr.: échelle de temps de formation d'étoiles   

The time necessary for a star to form. It depends inversely on the stellar mass.

star formation; → time scale.

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