The existence of a planet around a star and the star's metallicity is strongly correlated--but only in the case of low-mass stars. A new study suggests that no such correlation exist among giant stars. It is possible that the observed metallicity is not intrinsic, but pollution from protoplanetary disks. When a star expands into a giant, its atmosphere becomes better mixed and the extra metals disappear.

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Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.
-- Richard Feynman