In an effort to improve the utility of the helium burning red clump luminosity as a distance indicator , we explore the sensitivity of the K-band red clump absolute magnitude [ M _ { K } ( RC ) ] to metallicity and age .
We rely upon JK photometry for 14 open clusters and two globulars from the 2nd Incremental Data Release of the 2MASS Point Source Catalog .
The distances , metallicities , and ages of the open clusters are all on an internally consistent system , while the K ( RC ) values are measured from the 2MASS data .
For clusters younger than \sim 2 Gyr , M _ { K } ( RC ) is insensitive to metallicity but shows a dependence on age .
In contrast , for clusters older than \sim 2 Gyr , M _ { K } ( RC ) is influenced primarily by the metallicity of the population and shows little or no dependence on the age .
Theoretical red clump models based on the formalism of Girardi et al .
reinforce this finding .
Over comparable metallicity and age ranges , our average M _ { K } ( RC ) value is in accord with that based on solar-neighborhood red clump stars with HIPPARCOS parallaxes .
Lastly , we compute the distance to the open cluster NGC 2158 using our red clump calibration .
Adopting an age of 1.6 \pm 0.2 Gyr and [ Fe / H ] = -0.24 \pm 0.06 , our calibration yields a distance of ( m - M ) _ { V } = 14.38 \pm 0.09 .