Multiband Photometry of Rich Abell Clusters: Constraints on the Dwarf Star Content of Dark Matter

We present results of large-aperture (~1') JK photometry and CCD BVRI photometry near the centers of three distant (0.11 ≤ z ≤ 0.22), rich Abell clusters of galaxies. The colors of the integrated light are consistent with those of nearby E and S0 galaxies. The absence of anomalous reddening implies that no more than 2 h-1% (1 σ limit) of the dark matter in these clusters can be in the form of low-mass (~0.1 M☉) subdwarfs or old disk dwarfs. The limit increases to 3 h-1% if expressed in terms of zero-metallicity dwarfs. These results constrain the mass function of baryonic objects which might contribute to the dark matter.