2006-12-13 08:14:56 · 4 answers · asked by dpsgriffiths 1 in Science & Mathematics ➔ Astronomy & Space
21 cm radiation is emitted by hydrogen, the most abundant element in the universe. Since only a very small fraction of the hydrogen is udergoing this emission at any given time, this spectral line is very distinct and sharp.
By observing doppler shifts and broadening of this spectral line, astronomers can determine the relative velocities of stars and nebulae, which are comprised mostly of hydrogen. The rotation rate of our own galaxy and the mass of other galaxies have been determined this way.
2006-12-13 08:41:58 · answer #1 · answered by Meresa 3 · 0⤊ 0⤋
21cm line is produced by ability of unattached independent Hydrogen got here across interior the nebulae and interstellar clouds. this is a subtle distinction between 2 states of independent Hydrogen and being in Microwave part of spectrum, unabsorbed by ability of the interstellar medium. Galaxies are often the interstellar airborne dirt and mud & nebulae serving as nurseries for sparkling famous guy or woman structures. that's the main technique that is going on in galaxies. {your selection of solutions does not adventure}
2016-12-11 08:29:16 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Meresa is basically right. It's also the wavelength of the "background" radiation, present in every direction, and is the earliest signature we can detect of the Big Bang.
2006-12-13 09:16:50 · answer #3 · answered by JIMBO 4 · 0⤊ 0⤋
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2006-12-13 08:24:01 · answer #4 · answered by Anonymous · 0⤊ 0⤋