An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 247 Search : star
Blazhko star
  ستاره‌ی ِ بلاژکو   
setâre-ye Blazhko

Fr.: étoile à effet Blazhko   

A star showing the → Blazhko effect.

Blazhko effect; → star.

blue halo star
  ستارگان ِ آبی ِ هاله   
setâregân-e âbi-ye hâlé

Fr.: étoiles bleues du halo   

A star belonging to a variety of stars located above the → horizontal branch and blueward of the → red giant branch in the → Hertzsprung-Russell diagram of the → halo population.

blue; → halo; → star.

Setâregân plural of setâré, → star, âbi, → blue, hâlé, → halo.

blue HB star
  ستاره‌ی ِ BHB   
setâre-ye BHB

Fr.: étoile BHB   

Same as → blue horizontal branch star.

blue; → horizontal; → branch; → star.

blue hook star
  ستاره‌ی قلاب آبی   
setare-ye qollab-e abi

Fr.: étoile du crochet bleu   

A rare class of → horizontal branch (HB) stars that so far have been found in only very few Galactic → globular clusters. These stars are such called because they form a blue hook at the hot end of the HB in → far ultraviolet (FUV) → color-magnitude diagrams. The physical mechanism that produces blue hook populations is still uncertain. At least two scenarios have been proposed.
In the first scenario these stars are explained as a consequence of extreme → mass loss during the → red giant branch phase and late helium flashing while descending the → white dwarf cooling track. Due to the thin residual hydrogen envelope, helium is mixed into the envelope and hydrogen is mixed into the core during the late → helium flash. As a result, the stars are hotter and UV-fainter than canonical → extreme horizontal branch stars (EHB).
By contrast, in the He self-enrichment scenario the EHB and blue hook stars are produced via the normal evolution of He-enriched sub-populations in globular clusters. These sub-populations might have formed from the ejecta of intermediate-mass → asymptotic giant branch (AGB) stars of the first generation of stars. For the same age and → metallicity, He-enriched HB stars have smaller masses than normal HB stars, resulting in bluer → zero age horizontal branch star (ZAHB) locations. They are also brighter in the FUV, but this effect is reversed for very hot He-enriched HB stars with → effective temperatures larger than 19000 K.
See Dieball A., et al., 2013, arXiv:0901.1309v1, and for blue hook stars in ω Cen cluster, M. Tailo et al., 2015, Nature 523, 318.

blue; → hook; → star.

blue horizontal branch star
  ستاره‌ی ِ آبی ِ شاخه‌ی ِ افقی   
setâre-ye âbi-ye šâxe-ye ofoqi

Fr.: étoile bleue de la branche horizontale   

A member of a population of blue stars appearing on the → horizontal branch in the → Hertzsprung-Russell diagram of the Galactic → halo populations and → globular clusters. Belonging to → spectral types B3 to A0, they have evolved past the → red giant stage and are burning helium in their core.

blue; → horizontal; → branch, → star.

born-again AGB star
  ستاره‌یِ AGBیِ باز‌زاده   
setâre-ye AGB-ye bâzzâdé

Fr.: étoile AGB recyclée   

A → post-AGB star that undergoes a last → thermal pulse when it is already on the → white dwarf  → cooling track. The thermal pulse will expand the hot central star, whereby hydrogen will be ingested into the → helium burning shell. This will temporarily return the star to the → AGB phase it has previously left.

born; → again; → asymptotic giant branch; → star.

Bq star
  ستاره‌ی Bq   
setâre-ye Bq

Fr.: étoile Bq   

An obsolete designation used in early objective-prism studies to denote → B-type stars with "abnormal spectra" characterized by → forbidden emission lines. → B[e] star.


burst of star formation
belk-e diseš-e setâregân

Fr.: flambée de formation d'étoiles   

An intense → star formation activity in a region of → interstellar medium or, more globally, in a → galaxy. It is characterized by a → star formation rate which is much higher than the corresponding average. Same as → starburst.

burst; → star; → formation.

B[e] star
  ستاره‌یِ B[e]   
setâre-ye B[e]

Fr.: étoile B[e]   

A → Be star with → forbidden lines in emission in its spectrum. B[e] stars show large → infrared excess due to → circumstellar dust emission. See also → supergiant B[e] star, → pre-main sequence B[e] star, → compact planetary nebula B[e] star, → symbiotic B[e] star, and → unclassified B[e] star.

B, referring to the spectral type; e for emission lines, brackets for distinction from Be; → star.

carbon star
  ستاره‌ی ِ کربونی   
setâre-ye karboni

Fr.: étoile carbonée   

A class of → red giant stars whose spectra show strong → molecular bands of → carbon compounds.

carbon; → star.

carbon-enhanced metal-poor star (CEMP)
  ستاره‌ی ِ کم‌فلز ِ کربون بلندیده   
setâre-ye kamfelez-e karbon bolandidé

Fr.: étoile pauvre en métaux enrichie en carbon   

A star that presents very low → iron  → abundances [Fe/H] < -4 but an → anomalous richness in carbon. CEMP stars have been defined as a subset of → metal-poor stars that exhibit elevated [C/Fe] ≥ +1.0. It has been recognized that ~15-20% of stars with [Fe/H] < -2.0 are carbon enhanced. This fraction rises to 30% for [Fe/H] < -3.0, to 40% for [Fe/H] < -3.5, and ~75% for [Fe/H] < -4.0. This increasing trend of CEMP-star frequency with declining [Fe/H] is confirmed by the observation of many thousands of CEMP stars (Daniela Carollo + ApJ 2014, 788, 180). See also → extremely metal-poor star (EMPS)

carbon; → enhance; → metal; → metal; → poor; → star.

circumpolar star
  ستاره‌ی ِ پیراقطبی   
setâre-ye pirâqotbi (#)

Fr.: étoile circumpolaire   

Star that, from a given observer's → latitude, does not rise or set, but circles around the → celestial pole. To be circumpolar, a star must have a polar distance that is less than the observer's latitude. Whether a given star is circumpolar at the observer's latitude (φ) may be calculated in terms of the star's → declination (δ). The star is circumpolar if φ + δ ≥ +90° (observer in northern hemisphere), or φ + δ ≤ -90° (observer in southern hemisphere).

circumpolar; → star.

classical T Tauri star
  ستاره‌ی ِ T-گاو ِ کلاسیک   
setâre-ye T-Gâv-e kelâsik

Fr.: étoile T Tauri classique   

A → T Tauri star in which → accretion from a → circumstellar disk is responsible for ultraviolet and infrared excess emission and for a moderate to strong emission line spectrum superimposed on the photospheric spectrum. Classical T Tauri stars probably evolve into → weak-line T Tauri stars when their disks are fully accreted by the stars.

classical; → T Tauri star.

close binary star
  ستاره‌ی ِ دورین ِ کیپ   
setâre-ye dorin-e kip

Fr.: étoile binaire serrée   

A binary system in which the separation of the component stars is comparable to their diameters, so that they influence each other's evolution most commonly by the tidal forces.

close; → binary; → star.

CNO star
  ستاره‌ی ِ CNO   
setâre-ye CNO

Fr.: étoile CNO   

A late → O-type star or an early → B-type star in whose spectrum the lines of some of the elements → carbon (C), → nitrogen (N), and → oxygen (O) are present.

CNO; → star.

cocoon star
  ستاره‌ی ِ پیله‌ای   
setâre-ye pileyi

Fr.: étoile dans son cocon   

A star hidden in a dense envelope of gas and dust which is a strong source of infrared emission.

Cocoon nebula; → star.

collapsed star
  ستاره‌ی ِ رمبیده   
setâre-ye rombidé

Fr.: étoile effondrée   

A star that has undergone → collapse.

Collapsed p.p. of → collapse; → star.

Setâré, → star; rombidé p.p. of rombidan, → collapse.

collective star formation
  دیسش ِ گرد‌آمدی ِ ستارگان   
diseš-e gerdâmdi-ye setâregân

Fr.: formation collective d'étolies   

Formation of stars, especially → massive stars, in group as opposed to individual formation.

collective; → star; → formation.

compact binary star system
  راژمان ِ درین ِ همپک   
râžmân-e dorin-e hampak

Fr.: système binaire compact   

A binary star system which is composed of a collapsed object (→ degenerate dwarf, → neutron star, or → black hole) in orbit with a low-mass (≤ 0.5 Msol) secondary star, wherein the collapsed star → accretes matter from its → companion. These two objects form a binary system of overall dimensions 106 km with an orbital period of only hours or less. See also: → X-ray binary.

compact; → binary; → star; → system.

compact planetary nebula B[e] star (cPNB[e])
  ستاره‌یِ B[e]ی ِ میغ ِ سیاره‌ای ِ همپک   
setâre-ye B[e]-ye miq-e sayyâre-yi-ye hampak

Fr.: étoile de nébuleuse planétaire compacte   

A star whose spectrum shows striking similarities to → B[e] stars and is evolving into a → planetary nebula (→ preplanetary nebula).

compact; → planetary; → nebula; → B[e] star.

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