"First light" stellar spectra from Giraffe (detail)

A zoomed-in view of ESO Press Photo eso0219. The three strong absorption lines that are visible as horizontal, dark lines in the lower part of the photo are due to the common element Magnesium in the atmospheres of these stars (the Mg b triplet at wavelength 517 nm). The different intensity of the spectra is due to the different brightness of the stars.