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A P Cygni profile is an emission spectral line shape that shows an adjacent, slightly-blueshifted (i.e., slightly shorter wavelength) absorption line. The emission line indicates some thin material (i.e., optically thin) and the absorption feature indicates similar material (i.e., producing a line with the same rest wavelength) but that is moving toward the observer. The term is named for the star P Cygni which shows spectral lines (e.g., for H-alpha) with such a shape due to its stellar wind, from material moving outward from the star in all directions (producing the emission feature) and the same material in front of the star coming toward Earth (producing the shifted absorption feature).