An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 272 Search : 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.

W Virginis star
  ستاره‌ی ِ W-دوشیزه   
setâre-ye W dušizé

Fr.: étoile de type W Virginis   

A member of a class of → pulsating stars with a period of 1 to 35 days located in the → instability strip of the → H-R diagram. Also known as type II Cepheid variables, W Virginis stars are typically 1.5 mag fainter than classical Type I Cepheids and have a mass less than that of the Sun. They also exhibit a period-luminosity relation which is distinct, but works in a similar way to the relation for Type I Cepheids. Hence W Virginis stars can also be used to measure Galactic and extragalactic distances.

W, alphabetical letter; → variable star designation; → Virgo; → star.

W-R star
  ستاره‌ی ِ W-R   
setâre-ye W-R (#)

Fr.: étoile W-R   

Short for → Wolf-Rayet star.

Wolf-Rayet star.

Washington Double Star Catalog
  کاتالوگ ِ ستارگان ِ دوتایی ِ واشینگتن   
kâtâlog-e setâregân-e dotâyi-ye Washington

Fr.: Washington Double Star Catalogue   

A stellar catalog which is the world's principal database of astrometric → double star information. It is maintained by the United States Naval Observatory. The WDS Catalog contains positions (J2000), discoverer designations, epochs, position angles, separations, magnitudes, spectral types, proper motions, and, when available, Durchmusterung numbers and notes for the components of 142552 systems (as of Feb 27 2018).

Washington, referring to the location of the United States Naval Observatory in Northwest Washington, D.C; → double; → star; → catalog.

WC4 star
  ستاره‌ی WC4   
setâre-ye WC4

Fr.: étoile WC4   

A → WC Wolf-Rayet that its spectrum shows the following emission line characteristics: strong C IV 5801-12 Å, weak or absent C II 4267 Å, and moderate O V 5572-98 Å.

W, from → Wolf-Rayet; C, from → carbon; → star.

WC5 star
  ستاره‌ی WC5   
setâre-ye WC5

Fr.: étoile WC5   

A → WC Wolf-Rayet whose spectrum shows the following emission line characteristics: C III 5696 Å very weaker than C IV 5801-12 Å and C III weaker than O V 5572-98 Å.

W, from → Wolf-Rayet; C, from → carbon; → star.

WC6 star
  ستاره‌ی WC6   
setâre-ye WC6

Fr.: étoile WC6   

A → WC Wolf-Rayet whose spectrum shows the following emission line characteristics: C III 5696 Å very weaker than C IV 5801-12 Å and C III stronger than O V 5572-98 Å.

W, from → Wolf-Rayet; C, from → carbon; → star.

WC7 star
  ستاره‌ی WC7   
setâre-ye WC7

Fr.: étoile WC7   

A → WC Wolf-Rayet with a spectrum shows the following emission line characteristics: C III 5696 Å weaker than C IV 5801-12 Å and C III very stronger than O V 5572-98 Å.

W, from → Wolf-Rayet; C, from → carbon; → star.

WC8 star
  ستاره‌ی WC8   
setâre-ye WC8

Fr.: étoile WC8   

A → WC Wolf-Rayet with a spectrum shows the following emission line characteristics: C III 5696 Å stronger than C IV 5801-12 Å, C II 4267 Å absent, and O V 5572-98 Å weak or absent.

W, from → Wolf-Rayet; C, from → carbon; → star.

WC9 star
  ستاره‌ی WC9   
setâre-ye WC9

Fr.: étoile WC9   

A → WC Wolf-Rayet whose spectrum shows the following emission line characteristics: C III 569 Å stronger than C IV 5801-12 Å, C II 4267 Å present, and O V 5572-98 Å weak or absent.

W, from → Wolf-Rayet; C, from → carbon; → star.

weak emission-line central star (wel)
  ستاره‌ی ِ مرکزی با خط ِ گسیلی ِ نزار   
setâre-ye markazi bâ xatt-e gosili-ye nezâr

Fr.: étoile centrale à faibles raies d'émission   

A member of a class of cntral stars of planetary nebula, → CSPN, which have weaker and narrower emission lines than → Wolf-Rayet-like CSPNe (Tylenda et al. 1993, A&AS 102, 595).

weak; → emission; → line.

weak-line T Tauri star
  ستاره‌ی ِ T-گاو با خط‌های ِ نزار   
setâre-ye T-Gâv bâ xatthâ-ye nezâr

Fr.: étoile T Tauri à raies faibles   

A T Tauri star that lacks strong emission lines in its optical spectrum, and lacks both strong → stellar wind and → infrared excess. These objects are believed to be → pre-main sequence stars without obvious signs for disk → accretion. Weak-line T Tauri stars result from the evolution of → classical T Tauri stars.

weak; → line; → T Tauri star.

weak-wind O-type star
  ستاره‌ی ِ O با باد ِ نزار، ~ ~ ~ ~ کمزور   
setâre-ye O bâ bâd-e nezâr, ~ ~ ~ ~ kamzur

Fr.: étoile O de faible vent   

A → main sequence → O star with low luminosity and surprisingly weak → stellar wind compared to "classical" dwarfs. The → mass loss rates are lower than 10-8 solar masses per year and the → modified wind momenta nearly 2 orders of magnitude smaller than that expected from wind models for typical O stars. Weak-wind O-type stars occur in both → metal-rich and → metal-poor environments. Their nature is not yet fully understood. same as → weak wind problem.

weak; → wind; → O-type star.

WN/WC star
  ستاره‌ی ِ WN/WC   
setâre-ye WN/WC

Fr.: étoile WN/WC   

An object showing signatures of both → WN Wolf-Rayet stars and → WC Wolf-Rayet stars in the same spectrum, originating from individual stars rather than from WN + WC → binary systems. Such a WN/WC signature implies that the surface composition of the star is → nitrogen and → carbon enriched. This hybrid state results from a mixing process between He-burning → convective core and the overlying nitrogen enriched layers. According to model predictions, this situation corresponds to a short transition phase, lasting 103 to 104 years, during which a WN star evolves into a WC star. The WN/WC stars so far detected are all of early types.

WN Wolf-Rayet; → WC Wolf-Rayet.

WN10 star
  ستاره‌ی ِ WN10   
setâre-ye WN10

Fr.: étoile WN10   

A → WN Wolf-Rayet star whose spectrum shows the following emission line characteristics: N III 4634-4641, 5314 Å as strong as N II 3995 Å, Balmer lines, He I with → P Cygni profile.

W, from → Wolf-Rayet; N, from → nitrogen; → star.

WN11 star
  ستاره‌ی ِ WN11   
setâre-ye WN11

Fr.: étoile WN11   

A → WN Wolf-Rayet star whose spectrum shows the following emission line characteristics: N II 3995 Å as strong as He II 4686 Å, N III 4634-4641, 5314 Å weak or absent, Balmer lines, He I with → P Cygni profile.

W, from → Wolf-Rayet; N, from → nitrogen; → star.

WN2 star
  ستاره‌ی ِ WN2   
setâre-ye WN2

Fr.: étoile WN2   

A → WN Wolf-Rayet star whose spectrum shows the following emission line characteristics: N V 4603, 4619 Å weak or absent,He II 4686 Å strong.

W, from → Wolf-Rayet; N, from → nitrogen; → star.

WN2.5 star
  ستاره‌ی ِ WN2.5   
setâre-ye WN2.5

Fr.: étoile WN2.5   

A → WN Wolf-Rayet star whose spectrum shows the following emission line characteristics: N V 4603, 4619 Å present, N IV 3479-3484, 4058 Å absent.

W, from → Wolf-Rayet; N, from → nitrogen; → star.

WN3 star
  ستاره‌ی ِ WN3   
setâre-ye WN3

Fr.: étoile WN3   

A → WN Wolf-Rayet star whose spectrum shows the following emission line characteristics: N IV 3479-3484, 4058 Å very weaker than N V 3479-3484, 4058 Å and N III 4634-4641, 5314 Å weak or absent.

W, from → Wolf-Rayet; N, from → nitrogen; → star.

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