An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1333
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.

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 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.

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

Fr.: région de formation d'étoiles   

A region in which → star formation is going on.

star; → formation; → region.

  ستاره-بلک، بلک ِ ستاره   
setâre-belk, belk-e setâré

Fr.: flambée d'étoiles   

Simultaneous formation of a large number of stars in a region of a galaxy at an exceptionally high rate, compared to the usual star formation rates seen in most galaxies.

star; → burst.

starburst galaxy
  کهکشان ِ ستاره-بلک   
kahkešân-e setâre-belk

Fr.: galaxie à flambée d'étoiles   

A galaxy showing a short-lived intense period of star formation that is unsustainable over the → Hubble time due to the limited supply of gas within a galaxy. Starburst galaxies were first classified by Searle & Sargent (1972) and Searle et al. (1973), based on the blue colors produced by the → massive stars formed during the burst. In the local Universe, starbursts create approximately 10% of the radiant energy and 20% of the massive stars. At z = 1, starburst characteristics are found in 15% of galaxies, presumably attributable to the greater amounts of gas typically present in young galaxies and increased galactic interactions. The starburst's impact on a galaxy and the surrounding → intergalactic medium is primarily due to the consumption of gas that fuels the burst and the feedback from massive stars formed in the burst (McQuinn et al. 2010, astro-ph/1008.1589).

starburst; → galaxy.

Stark effect
  اُسکر ِ اشتارک   
oskar-e Stark

Fr.: effet Stark   

The → splitting of spectral lines of atoms and molecules due to the presence of an external electric field, which slightly changes the → energy levels of the atom. → Zeeman effect.

Named after Johannes Stark (1874-1957), a German physicist, and Physics Nobel Prize laureate (1919); → effect.


Fr.: tremblement d'étoile   

An astrophysical phenomenon that occurs when the crust of a → neutron star undergoes a sudden adjustment, analogous to an → earthquake on Earth. Starquakes are thought to be caused by huge → stresses exerted on the surface of the neutron star produced by twists in the ultra-strong interior → magnetic fields. They are thought to be the source of the intense → gamma-ray bursts that come from → soft gamma repeaters.

star; → quake.


Fr.: tache stellaire   

A phenomenon similar to a → sunspot but occurring on the surface of a star other than Sun. Due to spatial resolution constraints, starspots so far observed are in general much larger than those on the Sun, up to about 30% of the stellar surface may be covered, corresponding to sizes 100 times greater than those on the Sun.

star; → spot.

estât- (#)

Fr.: stat-   

A prefix attached to the name of a practical electrical unit indicating that it is part of the → CGS electrostatic system, e.g. statcoulomb, statvolt. These units are also indicated by the notation → esu (as in "volt esu").

Combining form representing → electrostatic, → -stat


Fr.: stat-coulomb   

A unit of → electric charge in the electrostatic → cgs system of units; equal to the charge that exerts a force of 1 → dyne on an equal charge at a distance of 1 cm under vacuum; equal to 3.3356 x 10-10 → coulombs. Same as → electrostatic unit (esu).

stat-; → coulomb.

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