2004ApJ...616..319C

This paper presents the near-IR imaging observations of CB 107, a small dark globule projected against a rich stellar background. By means of accurate photometry, the near-IR two-color diagram J-H versus H-K was obtained for the stellar background. This information was used to estimate the color excesses of the detected stars so that, given the reddening curve, it was possible to derive the extinction map of the cloud. The structural properties of the dark globule were investigated by plotting the extinction dispersion σ_AV, obtained in a given spatial box, as a function of the mean extinction A_V. This relationship has shown quite a definite linear behavior, with the slope increasing with the box size. The results of the present analysis, compared with those obtained by other authors on larger dark clouds, suggest that for a given spatial scale the slope of the σ_AVversus A_Vrelation is greater in CB 107 than in larger clouds. The so-called Δ-variance method was also used to investigate the structure of the dark globule by evaluating the drift behavior of its extinction map. In this way, we have found that the power spectrum of the extinction map is characterized by a power law with exponent β∼2.7. This value is lower than expected, for the same range of spatial scales, on the basis of previous work on large molecular clouds.