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: 261 Search : 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.

WN3/O3 star
  ستاره‌ی ِ WN3/O3   
setâre-ye WN/O3

Fr.: étoile WN3/O3   

A new type of → Wolf-Rayet stars found in the → Large Magellanic Cloud (LMC). These stars have both strong → emission lines, as well as → He II lines and → Balmer lines in absorption and spectroscopically resemble a → WN3 and → O3V binary pair. However, they are visually too faint to be WN3+O3 V → binary systems. So far nine WN3/O3 types have been detected, making up ~ 6% of the population of LMC WRs. Their temperatures are estimated to be around 100,000 K, a bit hotter than the majority of → WN Wolf-Rayet stars (by around 10,000 K) although a few hotter WNs are known. The abundances are what you would expect for → CNO equilibrium. However, most anomalous are their → mass-loss rates which are more like that of an → O star than a WN star. While their evolutionary status is uncertain, their low mass-loss rates and → wind velocities suggest that they are not products of homogeneous evolution. It is possible instead that these stars represent an intermediate stage between O stars and WNs. Since WN3/O3 stars are unknown in the Milky Way, their formation would depend upon → metallicity (Neugent et al., 2017, arxiv:1704.05497).

WN3; → O3; → star.

WN4 star
  ستاره‌ی ِ WN4   
setâre-ye WN4

Fr.: étoile WN4   

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

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

WN4.5 star
  ستاره‌ی ِ WN4.5   
setâre-ye WN4.5

Fr.: étoile WN4.5   

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

WN5 star
  ستاره‌ی ِ WN5   
setâre-ye WN5

Fr.: étoile WN5   

A → WN Wolf-Rayet star whose spectrum shows the following emission line characteristics: N III 4634-4641, 5314 Å as strong as N IV 3479-3484, 4058 Å as strong as N V 3479-3484, 4058 Å.

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

WN6 star
  ستاره‌ی ِ WN6   
setâre-ye WN6

Fr.: étoile WN6   

A → WN Wolf-Rayet star whose spectrum shows the following emission line characteristics: N III 4634-4641, 5314 Å about N IV 3479-3484, 4058 Å and N V 3479-3484, 4058 Å present, but weak.

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

WN7 star
  ستاره‌ی ِ WN7   
setâre-ye WN7

Fr.: étoile WN7   

A → WN Wolf-Rayet star whose spectrum shows the following emission line characteristics: N III 4634-4641, 5314 Å stronger than N IV 3479-3484, 4058 Å, N III weaker than He II 4686 Å, He I weak with → P Cygni profile.

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

WN8 star
  ستاره‌ی ِ WN8   
setâre-ye WN8

Fr.: étoile WN8   

A → WN Wolf-Rayet star whose spectrum shows the following emission line characteristics: N III 4634-4641, 5314 Å very stronger than N IV 3479-3484, 4058 Å, N III about He II 4686 Å, and He I with → P Cygni profile.

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

WN9 star
  ستاره‌ی ِ WN9   
setâre-ye WN9

Fr.: étoile WN9   

A → WN Wolf-Rayet star whose spectrum shows the following emission line characteristics: N III 4634-4641, 5314 Å stronger than N II 3995 Å, N IV 3479-3484, 4058 Å absent, He I with → P Cygni profile.

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

Wolf-Rayet star
  ستاره‌ی ِ وُلف-رایه   
setâre-ye Wolf-Rayet

Fr.: étoile Wolf-Rayet   

A type of very luminous, very hot (as high as 50,000 K) stars whose spectrum is characterized by broad emission lines (mainly He I and He II), which are presumed to originate from material ejected from the star at very high (~ 2000 km s-1) velocities. The most massive → O stars (M > 25 → solar masses for → solar metallicity) become W-R stars around 2 and 3 million years after their birth, spending only some few hundreds of thousands of years (≤ 106 years) in this phase until they explode as → type Ib and → type Ic supernovae. The minimum stellar mass that an O star needs to reach the W-R phase and its duration is dependent on → metallicity. → WC Wolf-Rayet; → WNE Wolf-Rayet; → WNL Wolf-Rayet; → WO Wolf-Rayet. For a review see: P. A. Crowther, 2007, Annu. Rev. of Astron. Astrophys. 45, 177.

Named after the French astronomers Charles Wolf (1827-1918) and Georges Rayet (1839-1906), of the Paris Observatory. In 1867 they discovered three stars in the constellation Cygnus (now designated HD191765, HD192103, and HD192641), that displayed broad emission bands in their spectra; → star.

X-ray Dim Isolated Neutron Star (XDINS)
  ستاره‌ی ِ نوترونی با پرتوهای ِ ایکس ِ نزار   
setâre-ye notroni bâ partowhâ-ye X-e nazâr

Fr.: étoile à neutron de faibles rayons X   

A member of a class of isolated, radio-silent → pulsars with peculiar properties. They show a purely thermal spectrum at X-ray energies with no evidence for a high-energy, power-law component often detected in other → isolated neutron star classes. The X-ray luminosity is 1031 - 1032 erg s-1, fully consistent with surface blackbody emission with temperatures ~ 40-100 eV and (radiation) radii of a few kilometers, as derived from X-ray spectral fits. With the only exception of RX J1856.5-3754, broad absorption features have been found in all XDINSs. These features have energies ~ 300 - 700 eV, equivalent widths of ~ 50 - 150 eV and, as in the case of RX J0720.4-3125, may be variable.

X-ray; → dim; → isolated; → neutron; → star.

zero age horizontal branch star (ZAHB)
  ستاره‌ی ِ شاخه‌ی ِ افقی با سن ِ صفر   
setâre-ye šâxe-ye ofoqi bâ senn-e sefr

Fr.: étoile de la branche horizontale d'âge zéro   

A star that has arrived on the → horizontal branch after leaving the → red giant branch. It begins → helium burning in its core.

zero; → age; → horizontal; → branch; → star.

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