1917 Photographic Plate Spectrum (IMAGE)
Caption
The 1917 photographic plate spectrum of van Maanen's star from the Carnegie Observatories' archive. The pull-out box shows the strong lines of the element calcium, which are surprisingly easy to see in the century old spectrum. The spectrum is the thin, (mostly) dark line in the center of the image. The broad dark lanes above and below are from lamps used to calibrate wavelength, and are contrast-enhanced in the box to highlight the two "missing" absorption bands in the star.
Credit
The Carnegie Institution for Science
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