On the Distribution of Dust in the Large Magellanic Cloud

Abstract

We present a detailed map of the reddening in a 1.9 x 1.5 degree section of the Large Magellanic Cloud, constructed from UBVI photometry of 2069 O and B main sequence stars. We use two reddening-free photometric parameters to determine the line-of-sight reddening to these stars. We find =0.20 mag, with a non-Gaussian tail to high values. When the reddening is corrected for foreground Galactic extinction, we find =0.13 mag. The line-of- sight values are then interpolated onto a uniform grid with a local least- squares plane fitting routine to construct a reddening map of the region. We use the distribution of reddening values to constrain the line-of-sight geometry of stars and dust in the LMC, and to test and normalize a standard extinction correction for galaxy photometry. We attempt to distinguish between line-of-sight depth effects and structure in the dust distribution as possible causes for the observed differential reddening through this region. We conclude that our data are consistent with a vertical exponential distribution of stars and dust in the LMC, for which the dust scale height is twice that of the OB stars; that the dust distribution must be non- uniform (clumpy) to account for the full distribution of measured reddening values; and that the B-band optical depth through the observed region of the LMC is 0.69 < tau < 0.82.