This value being nonzero for all known stars implies that Population III stars once existed, and stars are sorted into Population I and II based on this quantity.
The "problem" of this quantity pertains to it being about an order of lower magnitude than expected in high-redshift objects, including those in damped Lyman alpha absorbers. Objects with lower values of this quantity have a wider range of peculiar velocities according to the "this quantity"-velocity relation. Dwarf elliptical galaxies have unusually low measures of this quantity, which correlates with the color gradient of a galaxy. Pair-instability supernovae occur in objects with low values of this quantity. This value being nonzero for all known stars implies that Population III stars once existed, and stars are sorted into Population I and II based on this quantity. For objects other than the Sun, it is often given by the log of the ratio of iron to hydrogen in this object, divided by the same ratio for the Sun, in which the ratio is 1.8%. For 10 points, name this measure of the amount of non-hydrogen, non-helium matter in an astronomical object.
The "problem" of this quantity pertains to it being about an order of lower magnitude than expected in high-redshift objects, including those in damped Lyman alpha absorbers.
metallicity