enow.com Web Search

Search results

  1. Results from the WOW.Com Content Network
  2. Hydrogen line - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_line

    A hydrogen atom with proton and electron spins aligned (top) undergoes a flip of the electron spin, resulting in emission of a photon with a 21 cm wavelength (bottom) The hydrogen line, 21 centimeter line, or H I line [a] is a spectral line that is created by a change in the energy state of solitary, electrically neutral hydrogen atoms.

  3. Intensity mapping - Wikipedia

    en.wikipedia.org/wiki/Intensity_mapping

    In its most common variant, 21 cm intensity mapping, the 21cm emission line of neutral hydrogen is used to trace the gas. The hydrogen follows fluctuations in the underlying cosmic density field, with regions of higher density giving rise to a higher intensity of emission.

  4. Hydrogen spectral series - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_spectral_series

    For example, the 2 → 1 line is called "Lyman-alpha" (Ly-α), while the 7 → 3 line is called "Paschen-delta" (Pa-δ). Energy level diagram of electrons in hydrogen atom. There are emission lines from hydrogen that fall outside of these series, such as the 21 cm line.

  5. File:Fine hyperfine levels.svg - Wikipedia

    en.wikipedia.org/wiki/File:Fine_hyperfine_levels.svg

    The hyperfine splitting of the ground 2 S state is the source of the 21 cm hydrogen line, important in astronomy. Date: 16 May 2010: Source:

  6. Primeval Structure Telescope - Wikipedia

    en.wikipedia.org/wiki/Primeval_Structure_Telescope

    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.

  7. Hyperfine structure - Wikipedia

    en.wikipedia.org/wiki/Hyperfine_structure

    Hyperfine structure gives the 21 cm line observed in H I regions in interstellar medium. Carl Sagan and Frank Drake considered the hyperfine transition of hydrogen to be a sufficiently universal phenomenon so as to be used as a base unit of time and length on the Pioneer plaque and later Voyager Golden Record.

  8. AOL Mail

    mail.aol.com

    Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!

  9. Hydrogen Intensity and Real-time Analysis eXperiment

    en.wikipedia.org/wiki/Hydrogen_Intensity_and...

    This is accomplished by looking at the 21-cm line emission produced by hot diffuse neutral hydrogen from distant galaxy clusters and from the intracluster medium. [1] This neutral hydrogen traces out the large scale structures in the universe, and so can be used to map out the large scale Baryon Acoustic Oscillation (BAO) structure of the universe.