(physics, astronomy) A spectral line that corresponds to the absorption of electromagnetic radiation at a specific wavelength; the pattern of such lines is characteristic of specific atoms or molecules in the path of the radiation.
Other Word Forms of Absorption-line
Absorption-line Sentence Examples
The absence of lines of the spectrum of any element from the solar spectrum is no proof that the element is absent from the sun; apart from the possibility that the high temperature and other circumstances may show it transformed into some unknown mode, which is perhaps the explanation of the absence of nitrogen, chlorine and other non-metals; if the element is of high atomic weight we should expect it to be found only in the lowest strata of the sun's atmosphere, where its temperature was nearly equal to that of the central globe, and so any absorption line which it showed would be weak.
A few of the lines show a double reversal, the dark absorption line being greatly increased in breadth and showing a bright emission line in its centre.
The helium formations do not reach the sun's limb, and it is another puzzling detail that the spectrum of the disk shows no absorption line of anything like an intensity to correspond with the emission line of helium in the chromosphere.