Caption: The Emission line spectrum of iron (Fe, Z=26).
Probably neutral iron (i.e., Fe I), but original caption is silent.
Is the spectrum real or simulated? Hard to tell these days, but yours truly guesses simulated.
Credit/Permission: User:SeeSchloss,
before or circa 2006 /
Public domain.
Image link: Wikipedia:
File:Emission spectrum-Fe.png.
Local file: local link: line_spectrum_iron.html.
File: Spectra file:
line_spectrum_iron.html.