SIMBAD references

The K-band (2.2µm) is the most efficient band available for the detection of young stars embedded in molecular clouds. Consequently, many efforts to determine the initial mass function (IMF) of embedded stellar populations have focused on constraining the IMF with the K-band luminosity function (KLF). One caveat is that the shape of the KLF can be affected by a large and varying extinction from the surrounding molecular core. We examine here the effects of extinction on the KLF. We find that the resulting KLF is the convolution of the intrinsic KLF and a function describing the fraction of stars per interval of A_K. Applying this result to a power-law KLF, we find that extinction does not affect the shape of a power-law KLF. If the KLF is not a power-law, its form can be radically changed by extinction. We examine three idealized deviation from a power-law: a cutoff, a plateau, and a peak. In all of these cases, the resulting KLF shows little resemblance to the original KLF. This has important implications for recent attempts to date young clusters from the shape of their KLF and for searches for faint low mass stars and brown dwarfs in molecular cores. Finally, we address the problem of estimating the number of stars in a dense molecular core that obscures part of the embedded population. We present a simple method for calculating the fraction of embedded stars which are detected given the KLF and an estimate of the total extinction through the core.