A metallicity distribution function gives the number or mass of stars per metallicity interval. Its interpretation depends on sample selection, stellar lifetimes, spatial migration, and whether metallicity means total heavy-element abundance or a particular abundance ratio.
Changing from linear stellar metallicity to its logarithm multiplies the metallicity distribution function by its Jacobian determinant. A flat distribution in linear metallicity rises exponentially in logarithmic metallicity. The commonly used iron abundance coordinate is equivalent to total-metallicity scaling only if relative element abundances are fixed.
Articles by others on the same topic
The metallicity distribution function (MDF) is a statistical description of the metallicity, which refers to the abundance of elements heavier than hydrogen and helium in a celestial object, such as stars or galaxies. Metallicity is often expressed in terms of the logarithmic ratio of the abundance of a given element to that of hydrogen, relative to the solar abundance, commonly denoted as [Fe/H] (for iron) or other similar indices.