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: 2 Search : decrement
Balmer decrement
  کاهه‌ی ِ بالمر   
kâhe-ye Bâlmer

Fr.: décrément de Balmer   

The intensity ratio among the couple of relatively adjacent → Balmer lines, for example Hα/Hβ and Hβ/Hγ, which have well-known theoretical values. They are used to determine the → interstellar extinction.

Balmer; → decrement.

decrement
  کاهه   
kâhé

Fr.: décrément   

1) The amount lost in the process of decreasing.
2) Math.: The quantity by which a variable is decreased. A negative → increment.
3) Physics: 1) The ratio of the amplitude of an oscillation to that of its succeeding oscillation in an underdamped vibrating system. 2) The intensity ratio of a series of spectral lines of the same nature, such as → Balmer decrement.

L decrementum, from decre(tus), → decrease + -mentum noun suffix -ment.

Kâheh, from kâh- present stem of kâhidan, → decrease + noun suffix .