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We report results of a near--infrared imaging survey of L977, a dark cloud in Cygnus seen in projection against the plane of the Milky Way. We use measurements of the near--infrared color excess and positions of the 1628 brightest stars in our survey to measure directly dust extinction through the cloud following the method described by Lada et al. (1994). We spatially convolve the individual extinction measurements with a square filter 90 in size to construct a large-scale map of extinction in the cloud. We derive a total mass of M(L977)= (660 +/- 30)(D/500 pc)^2 Msun and, via a comparison of source counts with predictions of a galactic model, estimate a distance to L977 of 500 +/- 100 pc. We find a correlation between the measured dispersion in our extinction determinations and the extinction. We interpret this as evidence for the presence of structure on scales smaller than the 90 resolution of our extinction map. To further investigate the structure of the cloud we construct the frequency distribution of the 1628 individual extinction measurements in the L977 cloud. The shape of the distribution is similar to that of the IC 5146 cloud. Monte Carlo modeling of this distribution suggests that between 2 < Av < 40 mag (or roughly 1 < r < 0.1 pc) the material inside L977 is characterized by a density profile n(r) propto r^(-2). Direct measurement of the radial profile of a portion of the cloud confirms this result. (more...)
We report observations of the J =(1--0) C18O molecular emission line toward the L977 molecular cloud. To study the correlation between C18O emission and dust extinction we constructed a Gaussian smoothed map of the infrared extinction measured by Alv
We examine the three-dimensional structure and dust extinction properties in a ~ 200 pc $times$ 100 pc region in the southwest bar of the Small Magellanic Cloud (SMC). We model a deep Hubble Space Telescope optical color-magnitude diagram (CMD) of re
To elucidate the dust properties in the SMC we have for the first time measured linear polarization in five colors in the optical region of the spectrum for a sample of reddened stars. For two of these stars, for which there were no existing UV spect
Using near infrared UKIDSS Galactic Plane Survey data, we make extinction measurements to individual stars along the same line of sight as molecular clouds. Using an existing 3D extinction map of the inner Galaxy, that provides line of sight specific
We present a three dimensional (3D) extinction analysis in the region toward the supernova remnant (SNR) S147 (G180.0-1.7) using multi-band photometric data from the Xuyi Schmidt Telescope Photometric Survey of the Galactic Anticentre (XSTPS-GAC), 2M