Galaxy Zoo Talk

HI(21cm)source

  • isadora_paradijsvogel by isadora_paradijsvogel

    what is an HI(21cm)source?

    Posted

  • Capella05 by Capella05 moderator in response to isadora paradijsvogel's comment.

    Hi isadora,

    H I stands for neutral atomic hydrogen, so I guess this galaxy has had a spectrograph done that found it had concentrations of H I atoms. From doing a brief search on the internet, the 21 cm stands for the line where we would see this element.

    These regions do not emit detectable visible light (except in spectral
    lines from elements other than hydrogen) but are observed by the 21-cm
    (1,420 MHz) region spectral line - Wikipedia

    Chemistry is not my forte, so hopefully someone else with more knowledge can give you more info.

    Cheers.

    Posted

  • Budgieye by Budgieye moderator

    21cm is used in radio astronomy, which uses a longer wavelength of light than optical astronomy. It is a weak radio wave light but it penetrates dust clouds in our galaxy. It is used to calculate the speed at which the object is moving towards us and away from us. It is formed by the flip flop of spin of electrons, not by electron orbital level quantum transitions.

    enter image description here

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  • isadora_paradijsvogel by isadora_paradijsvogel

    Thanks for the explanations moderators
    Astronomers periodic table: http://www.periodicvideos.com/videos/feature_astronomer_table.htm

    Posted