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: 22 Search : crystal
uniaxial crystal
  بلور ِ یک‌آسه   
bolur-e yek-âsé

Fr.: cristal uniaxe   

Crystal with double refraction possessing only one → optic axis.

uni-; axial adj. from → axis; → crystal.

white dwarf crystallization
  بلورش ِ سفیدکوتوله   
bolureš-e sefid kutulé

Fr.: cristallisation de naine blanche   

The most important phenomenon occurring during → white dwarf evolution, which results from its cooling. Crystallization is a → phase transition whereby → latent heat is released. At the cooler end of a white dwarf's life (→ cooling time), the → thermal energy of nuclei, which are positively charged ions, becomes small and the effects of electrostatic interaction on the motion of ions become important. The ions repel each other and their distribution will be such that the → Coulomb energy per ion is a minimum. This will cause the ions to form crystal-like lattice structures. As the star cystallizes it releases latent heat, providing an additional energy source that slows the cooling process compared to the → Mestel theory. Once the bulk of the white dwarf is crystalline, heat can travel through the star more easily and the white dwarf cools faster.

white; → dwarf; → crystallization.


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