Palomar 14: A young globular cluster in the outer Galactic halo

We present deep BV CCD color-magnitude diagrams of the outer-halo Galactic globular cluster Palomar 14 based on observations taken at the 3.5 m WIYN and KPNO 4 m telescopes. Pal 14 is an intermediate metallicity ([Fe/H] = -1.60) cluster with a horizontal branch populated predominantly redward of the RR Lyrae instability strip. As such, it is affected by the ''second parameter effect'' which, in addition to metallicity, influences the morphology of the horizontal branch. From the position of the main sequence turnoff, we conclude that Pal 14 is 3 to 4 Gyr younger than typical globular clusters at its metallicity. Several other ''second parameter'' globular clusters have been found to be relatively young. All of this evidence, taken together, presents a powerful case in favor of age as the second parameter. (C) 1997 American Astronomical Society.