The metallicity of μ Leonis

Castro et al. (1996) have concluded that μ Leo has three times the solar metallicity. That conclusion is based on their own work and on rezeroed values of [Fe/H] from the literature. A review of their paper reveals that there are significant omissions from their list of literature results. In addition, their procedure for establishing zero points for values of [Fe/H] is found to be fallacious. If that zero-point procedure is nonetheless accepted at face value, and if Hyades data available at the time are used, the zero-point procedure yields metallicities for the Hyades giants that appear to differ from those for Hyades dwarfs. The difference is in the opposite sense to that found by Griffin & Holweger (1989). As a first step in resolving these problems, the zero-point procedure is discussed in some detail. Next, the Hyades problem is reconsidered by taking all published data into account. In agreement with a conclusion drawn by Taylor (1998b), no evidence is found for a metallicity difference between Hyades giants and Hyades dwarfs. Published values of [Fe/H] for μ Leo are then analyzed. The technique applied to those data avoids the zero-point problem described above. In addition, it permits the scatter in the μ Leo data to be compared to the scatter in data from about 1000 other stars. In agreement with Taylor (1996), it is found that the value of [Fe/H] for μ Leo does not conclusively exceed +0.2 dex. In addition, it is found that the scatter in the μ Leo data is consistent with data scatter for other stars. In contrast, the scatter in the data considered by Castro et al. is found to be unrealistically small. A number of pertinent issues raised by this review are highlighted to encourage future discussion.