hydrogen line

(redirected from 21-cm radiation)

hydrogen line

(21 cm line) See H I region.

hydrogen line

[′hī·drə·jən ‚līn]
(spectroscopy)
A spectral line emitted by neutral hydrogen having a frequency of 1420 megahertz and a wavelength of 21 centimeters; radiation from this line is used in radio astronomy to study the amount and velocity of hydrogen in the Galaxy.
References in periodicals archive ?
Lockman of the National Radio Astronomy Observatory used the new 100-meter Green Bank Telescope (GBT) in West Virginia to study the 21-cm radiation from neutral hydrogen in Smith's Cloud in much better detail than before.