Spectral energy distribution

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The SED of M51 (upper right) obtained by combining data at many different wavelengths, e.g. UV, visible, and infrared (left)

A spectral energy distribution (SED) is a plot of energy versus frequency or wavelength of light (not to be confused with a 'spectrum' of flux density vs frequency or wavelength).[1] It is used in many branches of astronomy to characterize astronomical sources. For example, in radio astronomy they are used to show the emission from synchrotron radiation, free-free emission and other emission mechanisms. In infrared astronomy, SEDs can be used to classify young stellar objects.

Detector for spectral energy distribution[edit]

The count rates observed from a given astronomical radiation source have no simple relationship to the flux from that source, such as might be incident at the top of the Earth's atmosphere.[2] This lack of a simple relationship is due in no small part to the complex properties of radiation detectors.[2]

These detector properties can be divided into

  • those that merely attenuate the beam, including
    1. residual atmosphere between source and detector,
    2. absorption in the detector window when present,
    3. quantum efficiency of the detecting medium,[2]
  • those that redistribute the beam in detected energy, such as
    1. fluorescent photon escape phenomena,
    2. inherent energy resolution of the detector.[2]

See also[edit]


  1. ^ "SED plots - CoolWiki". coolwiki.ipac.caltech.edu. Retrieved 27 February 2018.
  2. ^ a b c d Dolan JF (Aug 1972). "The Direct Reduction of Astronomical X-Ray Spectra". Astrophys. Space Sci. 17 (2): 472–81. Bibcode:1972Ap&SS..17..472D. doi:10.1007/BF00642917. S2CID 123125127.

Further reading[edit]

External links[edit]