hydrogen line

(redirected from Neutral hydrogen)

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 ?
By 380,000 years after the Big Bang, the universe had cooled enough for free electrons and protons to combine into neutral hydrogen atoms that filled the universe, allowing light to travel through the cosmos.
Objective: "I request ERC funding to set up a dedicated science team to detect, for the first time, the redshifted 21-cm radio line emission of neutral hydrogen (HI) with LOFAR coming from the first billion years of the age of the Universe (the Epoch of Reionization and the Dark Ages ).
In the cosmic dark ages, neutral hydrogen gas filled the universe.
The puzzling factors are the two elements that cause the ionisation of neutral hydrogen.
So, it is not necessarily that other distant galaxies are not there, but that they are hidden from detection behind a wall of neutral hydrogen fog, which blocks the hydrogen emission signal.
It uses intensity mapping of redshifted (z = 7-12) 21cm emission of neutral hydrogen to try to measure the power spectrum of fluctuations in the intergalactic medium introduced by the first luminous sources in the universe (see http://eor.
Using the GBT, Pisano was able to detect the glow emitted by neutral hydrogen gas connecting NGC 6946 with its cosmic neighbors.
Scientists think that the collision of neutral hydrogen molecules may have helped to drive the Martian atmosphere into space over billions of years.
It could be that they're hidden from detection behind a wall of neutral hydrogen fog, which blocks the hydrogen emission signal.
When molecular hydrogen delivers a single proton to the condensation reactions, it is also delivering a single electron, if a neutral hydrogen atom subsequently emits.
After outlining a brief history of radio astronomy, Brian Coleman described the physics behind the neutral hydrogen emission line.
When these protons from the solar wind hit the surface of the moon, some are scattered back as energetic neutral hydrogen atoms.