Definitions for hydrogen line
hy·dro·gen line

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1. hydrogen linenoun

   a spectral line of atomic hydrogen having a wavelength of about 21cm; used extensively in radio astronomy

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1. Hydrogen line

   The hydrogen line, 21 centimeter line, or H I line is the electromagnetic radiation spectral line that is created by a change in the energy state of neutral hydrogen atoms. This electromagnetic radiation has a precise frequency of 1420.405751768(2) MHz, which is equivalent to the vacuum wavelength of 21.106114054160(30) cm in free space. This frequency falls below the microwave region of the electromagnetic spectrum, which begins at 3.0 GHz (10 cm wavelength), and it is observed frequently in radio astronomy because those radio waves can penetrate the large clouds of interstellar cosmic dust that are opaque to visible light. This line is also the theoretical basis of the hydrogen maser. The microwaves of the hydrogen line come from the atomic transition of an electron between the two hyperfine levels of the hydrogen 1 s ground state that have an energy difference of 5.8743261841116(81) μeV [9.411708152678(13)×10−25 J]. It is called the spin-flip transition. The frequency, ν, of the quanta that are emitted by this transition between two different energy levels is given by the Planck–Einstein relation E = hν. According to that relation, the photon energy of a photon with a frequency of 1420.405751768(2) MHz is 5.8743261841116(81) μeV [9.411708152678(13)×10−25 J]. The constant of proportionality, h, is known as the Planck constant.

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1. Hydrogen line

   The hydrogen line, 21 centimeter line or HI line refers to the electromagnetic radiation spectral line that is created by a change in the energy state of neutral hydrogen atoms. This electromagnetic radiation is at the precise frequency of 1420.40575177 MHz, which is equivalent to the vacuum wavelength of 21.10611405413 cm in free space. This wavelength or frequency falls within the microwave radio region of the electromagnetic spectrum, and it is observed frequently in radio astronomy, since those radio waves can penetrate the large clouds of interstellar cosmic dust that are opaque to visible light. The microwaves of the hydrogen line come from the atomic transition between the two hyperfine levels of the hydrogen 1s ground state with an energy difference of 5.87433 µeV. The frequency of the quanta that are emitted by this transition between two different energy levels is given by Planck's equation.

How to pronounce hydrogen line?

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How to say hydrogen line in sign language?

Numerology

1. Chaldean Numerology

   The numerical value of hydrogen line in Chaldean Numerology is: 1

2. Pythagorean Numerology

   The numerical value of hydrogen line in Pythagorean Numerology is: 1

References

1. ^ Wiktionary
   https://en.wiktionary.org/wiki/Hydrogen_Line
2. ^ Wikipedia
   https://en.wikipedia.org/wiki/Hydrogen_Line
3. ^ Wikidata
   https://www.wikidata.org/w/index.php?search=hydrogen line