IS AGE REALLY THE 2ND PARAMETER IN GLOBULAR-CLUSTERS

From the close similarity of the magnitude difference between the tip of the red giant branch and the turnoff in the [Fe/H] ≈ - 1.3 globular clusters NGC 288, NGC 362, and M5, we infer that the ages of these three systems (and Palomar 5, whose horizontal branch is used to define its distance relative to the others) are not detectably different. An identical conclusion, by similar means, is reached for the [Fe/H] ≈ - 2.1 globular clusters M15, M30, M68, and M92. Several recent claims that age is responsible for the wide variation in horizontal-branch morphology among clusters of the same metal abundance are not supported.