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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

   Homepage   
   


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

<< < A s Bla com ext hor mul Pan pro S-t sta sup W V WN5 > >>

Number of Results: 249 Search : star
supermassive star
  ستاره‌ی ِ اَبَر-پرجرم   
setâre-ye abar-porerm

Fr.: étoile supermassive   

A star with an initial mass over about 120 solar masses. The existence of such stars is the present Universe is not confirmed. Such stars were proposed as an explanation for very bright O type stars in the Large Magellanic Cloud, but these are now known to be clusters of ordinary O stars. → very massive star; → massive star.

supermassive; → star.

supra-horizontal branch star
  ستاره‌ی ِ فراز ِ شاخه‌ی ِ افقی   
setâre-ye farâz-e šâxe-ye ofoqi

Fr.: étoile au-dessus de la branche horizontale   

A member of a rare class of objects found in → globular clusters to lie about one magnitude above and to the blue part of the → horizontal branch. These stars are identified as post → EHB stars on their way from to the → asymptotic giant branch.

supra-; → horizontal; → branch; → star.

symbiotic B[e] star (symB[e])
     
setâre-ye B[e]-ye hamzi

Fr.: étoile B[e] symbiotique   

A → B[e] star whose spectrum shows the presence of a cool component characterized mainly by → TiO bands.

symbiotic; → B[e] star.

symbiotic star
  ستاره‌ی ِ همزی   
setâre-ye hamzi

Fr.: étoile symbiotique   

A stellar object whose optical spectrum displays lines characteristic of gases of two very different temperatures, typically of an M star (3500 K) and a B star (20 000 K) superimposed. A symbiotic star is in fact a close binary system.

symbiotic; → star.

T Tauri star
  ستاره‌ی ِ T-گاو   
setâre-ye T-Gâv

Fr.: étoile T Tauri   

A member of a class of young stellar objects of roughly 1 solar mass showing strong → infrared excess emission attributed to → circumstellar disks and found within or close to molecular clouds. T Tauri stars are → protostars in the final stages of formation to become a stable → main sequence star. The nuclear reactions in their core have not yet stabilised and the stars are known for the variability of their brightness. See also → classical T Tauri star, → weak-line T Tauri star.

T Tauri; → star.

tight star cluster
  خوشه‌ی ِ ستاره‌ای ِ تنگ   
xuše-ye setâreyi-ye tang

Fr.: amas stellaire serré   

A cluster of stars in which members are closely situated so that high resolution observations are required to distinguish them individually.

tight; → star cluster.

triggered star formation
  دیسش ِ ماشه‌ای ِ ستاره   
diseš-e mâše-yi-ye setâré

Fr.: formation d'étoiles déclanchée   

The formation of second-generation stars in a → molecular cloud, as set off by the action of → massive stars. → sequential star formation; → radiation-driven implosion.

trigger; → star formation.

triple star
  ستاره‌ی ِ سه‌تایی   
setâre-ye setâyi

Fr.: étoile triple   

A group of three stars visually or physically associated with each other. → triple system.

triple; → star

turnoff star
  ستاره‌ی ِ رهگشت   
setâre-ye rahgašt

Fr.: étoile du tournant final de la séquence principale   

A star that has ended → hydrogen burning in its core but is still burning hydrogen in a shell that surrounds the core, just before evolving into a → red giant.

turnoff; → star.

Tycho's star
  ستاره‌ی ِ توگو   
setâre-ye Tycho

Fr.: étoile de Tycho   

A → supernova of Type Ia in the constellation → Cassiopeia, which Tycho Brahe observed in November 1572. At its peak it was as bright as Venus and was visible in the daytime, reaching a magnitude of about -4. It is now visible as a → supernova remnant about 20 light-years across at a distance of about 7,500 light-years. It is associated with faint emission in the optical and X-rays, but is a strong radio source. Other designations: SN 1572, 3C 10, B Cas, 2U 0022+63.

Named after the Danish astronomer Tycho Brahe (1546-1601), who described the event; → star.

ultraviolet star
  ستاره‌ی ِ فرابنفش، ~ ِ اولتر-بنفش   
setâre-ye farâbanafš, ~ ultar-banafš

Fr.: étoile ultraviolette   

A star, such as O types or hot central stars of planetary nebulae, which radiates essentially in the ultraviolet part of the electromagnetic spectrum.

ultraviolet; → star.

unclassified B[e] star (unclB[e])
  ستاره‌یِ B[e]ی ِ بی‌رده   
setâre-ye B[e]-ye bi radé

Fr.: étoile B[e] non-classée   

A temporary designation for a → B[e] star that cannot be placed in any of the four known classes.

classification; → B[e] star.

unreddened star
  ستاره‌ی ِ ناسرخیده   
setâre-ye nâsorxidé

Fr.: étoile non rougie   

A star whose light is not affected by→ interstellar absorption. → reddening

un-; → reddened star.

Ursa Major star cluster
  خوشه‌ی ِ خرس ِ بزرگ   
xuše-ye Xers-e Bozorg (#)

Fr.: amas de la Grande Ourse   

A moving star cluster containing over 100 stars that are scattered over an area of sky more than 1,000 minutes of arc in diameter. The five brightest stars of the → Big Dipper as well as → Sirius belong to this → dynamical stream.

Ursa Major; → star; → cluster.

UX Ori star
  ستاره‌ی ِUX شکارگر   
setâre-ye UX Šekârgar

Fr.: étoile UX Ori   

A star that shows large irregular brightness variations and belongs to the Herbig Ae/Be family, i.e. pre-main sequence stars of intermediate mass. Typically a decrease of 2-3 magnitudes in the visible occurs for a few days to a couple of weeks. Current theories explain this behavior as being an obscuration of the central star by orbiting dust clouds, as well as contribution to the total luminosity by unsteady accretion onto the central star. Also called UXOr.

U and X letters of alphabet, Ori, → Orion; → star.

variable star
  ستاره‌ی ِ ورتنده   
setâre-ye vartandé

Fr.: étoile variable   

A star whose luminosity changes over periods of time; there are many reasons and many types. → cataclysmic variable; → Cepheid; → pulsating star; → nova; → long-period variable; → short-period variable; → Luminous Blue Variable (LBV); etc.

variable; → star.

variable star designation
  نامگزینی ِ ستاره‌ی ِ ورتنده   
nâmgozini-ye setâre-ye vartandé

Fr.: designation des étoiles variables   

A set of conventions used for naming variable stars. Stars with existing → Bayer designations are not given new designations. Alternatively, the letters R through Z are used followed by the Latin genitive of the name of the hosting constellation. Otherwise, two letters of alphabet are used (334 combinations) with the Latin genitive of the name of the constellation. Finally, the letter V (variable) is used followed by numbers 335, 336, and so on. Some examples are: → P Cygni, → T Tauri, → FU Orionis, → EX Lupi, and V509 Cassiopeiae.

variable; → star; → designation.

very massive star
  ستاره‌ی ِ بسیار پرجرم   
setâre-ye besyâr porjerm

Fr.: étoile très massive   

A star of mass around 100 → solar masses. See also: → supermassive star, → massive star, → canonical upper limit.

very; → massive; → star.

violent star formation
  دیسش ِ سورای ِ ستارگان   
diseše surâ-ye setâregân

Fr.: formation violente d'étoiles   

The concept of star formation pertaining to a variety of systems (OB associations, giant H II regions, H II galaxies, massive star clusters, etc.) that are believed to have formed large numbers of stars in a very short time.

violent; → star formation.

Vz star
  ستاره‌ی ِ Vz   
setâre-ye Vz

Fr.: étoile de type Vz   

A class of → O-type stars whose spectra show He II 4686 absorption line much stronger than any other He line especially He II 4541 or He I 4471. Vz stars are thought to be young stars lying close to the → ZAMS (Walborn & Parker 1992, ApJ 399, L87). Alternatively, the Vz characteristics may be related to the wind properties rather than to the youth of the star (Martins et al., 2005, A&A 441, 735).

V indicating → main sequence, z for "zero age;" → star.

<< < A s Bla com ext hor mul Pan pro S-t sta sup W V WN5 > >>