An Etymological Dictionary of Astronomy and Astrophysics

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فرهنگ ریشه‌شناختی اخترشناسی-اخترفیزیک

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H-alpha
  H-آلفا  
H-âlfâ (#)
Fr.: H-alpha (Hα)  

The → Balmer series spectral line of hydrogen which results from → atomic transition between the → energy levels 2 and 3. It has a wavelength of 656.4 nm and falls in the red region of the visible spectrum.

See also: H, symbol of → hydrogen; alpha (α), the first letter of Gk. alphabet.