An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 1347
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.

star
  ستاره   
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 (SFE)
  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: εSFE = Mstars / (Mstars + Mgas).

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.

star S2
  ستاره S2   
setâré S2

Fr.: étoile S2   

A → main sequenceB-type star that orbits the → supermassive black hole candidate → Sgr A* in the → Galactic center. The star S2, which is bright enough for making detailed measurements, has a highly elliptical, 16-year-period orbit around Sgr A*. Near → pericenter at 120 → astronomical units, ~ 1400 → Schwarzschild radii, the star has an orbital speed of ~ 7650 km s-1, such that the first-order effects of → special relativity and → general relativity have become detectable with current capabilities (Auber et al., 2018, A&A 615, L15).

star.

star system
  راژمان ِ ستاره‌ای   
râžmân-e setâre-yi

Fr.: système stellaire   

Same as → stellar system.

stellar; → system.

star trail
  رد ِ ستاره   
radd-e setâré

Fr.: traînées stellaires   

A curved → path left by a star on an → imaging detector attached to a → telescope when the telescope does not keep up with the → rotation of the → Earth.

star; → trail.

star-forming galaxy
  کهکشان ِ دیسنده‌ی ِ ستاره   
kahkešân-e disnade-ye setâré

Fr.: galaxie de formation d'étoiles   

A galaxy that is located on the → galaxy main sequence in the plane relating → star formation rates to total stellar masses.

star; → formation; → galaxy.

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