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: 5 Search : giant branch
asymptotic giant branch (AGB)
  شاخه‌ی ِ ناهمساوی ِ غولان   
šâxe-ye nâhamsâvi-ye qulân

Fr.: branche asymptotique des géantes   

A region of the → Hertzsprung-Russell diagram populated by evolving → low-mass to → intermediate-mass stars. These stars have an electron → degenerate core of carbon and oxygen surrounded by two burning shells of helium and hydrogen. The H and He-burning shells are activated alternately in the deep layers of the star. An extended and tenuous convection envelope, having a radius of 104-105 times the size of the core, lies above these shells. The loosely bound envelope is gradually eroded by the strong → stellar wind, which forms a dusty → circumstellar envelope out to several hundreds of stellar radii. The convective envelope, stellar atmosphere, and circumstellar envelope have a rich and changing chemical composition provided by → nucleosynthesis processes in the burning shells in the deep interior.

symptotic; → giant; → branch.

giant branch
  شاخه‌ی ِ غولان، ~ غولپیکران   
šâxe-ye qulân, ~ qulpeykarân (#)

Fr.: branche des géantes   

A conspicuous family of stars in the → Hertzsprung-Russell diagram composed of red, evolved stars with large sizes. → giant star; → red giant.

giant; → branch.

post-asymptotic giant branch star (post-AGB)
  ستاره‌ی ِ پسا-شاخه‌ی ِ غولان ِ ناهمساوی   
setâre-ye pasâ-šâxe-ye qulân-e nâhamsâvi

Fr.: étoile post-asymptotique   

A star in a short-lived evolutionary stage evolving from the → asymptotic giant branch toward higher → effective temperatures. The majority of low and intermediate mass stars (1 to 8 → solar masses) are believed to pass through this stage on their way to becoming → planetary nebulae.

post-; → asymptotic giant branch.

red giant branch (RGB)
  شاخه‌ی ِ غولان ِ سرخ   
šâxe-ye qulân-e sorx

Fr.: branche des géantes rouges   

The evolutionary path of a star that has exhausted its available hydrogen content in the core, between the → main-sequence turnoff and the → helium flash.

red giant; → branch.

tip of the red giant branch method
  روش ِ نوک ِ شاخه‌ی غول‌های ِ سرخ   
raveš-e nok-e šâxe-ye qulhâ-ye sorx

Fr.: méthode du haut de la branche des géantes   

A technique for deriving extragalactic distances which uses the → luminosity of the brightest → red giant branch stars in old → stellar populations as a "standard candle." For old (> 2-3 Gyr), metal-poor ([Fe/H] < -0.7) stellar populations, this luminosity is relatively well determined, and the → absolute magnitude of these stars in the I band is roughly constant (MI = -4.1 ± 0.1).

M.E. tip; from M.L.G. or M.Du. tip "utmost point, extremity" (cf. Ger. zipfel, a diminutive formation); → red giant; → branch; → method.

Raveš, → method; nok "tip;" šâxé, → branch; qulhâ-ye sorx plural of qul-e sorx, → red giant.