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Deep HST photometry has recently been presented for the outer-halo globularclusters Palomar 4 and Eridanus. The new high-precision color-magnitudediagrams obtained for these globulars have allowed a measurement of their agesrelative to M5 (NGC 5904), which is a well-observed, much closer cluster.Assuming that the globular clusters share the same chemical composition, Pal4/Eridanus have been reported to be younger than M5 by ~1-2 Gyr, based on boththe magnitude difference between the horizontal branch (HB) and the turnoff andthe difference in color between the turnoff and the lower subgiant branch. Inthe present article, we address the following question: What age differencewould be required to account for the difference in HB types between M5 and Pal4/Eridanus, assuming age to be the "second parameter"? We find that, unless allthese clusters (including M5) are younger than 10 Gyr, such an age differenceis substantially larger than that based on an analysis of the cluster turnoffs.To reach such a conclusion, six different analytical mass loss rate formulae(reported in an Appendix), all implying a dependence of mass loss on the redgiant branch on age, were employed. Our results appear to be in conflict withclaims that age can be the only second parameter in the Galactic globularcluster system.Comment: 13 pages, including 11 postscript figures. The Astrophysical Journal,  in pres

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Horizontal‐Branch Models and the Second‐Parameter Effect. III. The Impact of Mass Loss on the Red Giant Branch and the Case of M5 and Palomar 4/Eridanus