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The internal structure of a dark globule CB52

1/5. The internal structure of a dark globule CB52. An optical and near-IR investigation. Berlinda M.T. Maiolo. Scuola Nazionale di Astrofisica Volterra (PI), october 2005. 2/5. Introduction.

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The internal structure of a dark globule CB52

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  1. 1/5 The internal structure of a dark globule CB52 An optical and near-IR investigation. Berlinda M.T. Maiolo Scuola Nazionale di Astrofisica Volterra (PI), october 2005

  2. 2/5 Introduction An important goal in the molecular cloud studies is to understand how interstellar medium produces clouds and how they are responsible for almost all star formation. Here we present an observational study of the internal structure of the small dark cloud, CB52 both in optical and near-IR range

  3. 3/5 Optical range (BVI) Color excess Star counts In a two color diagram the displacement, along the reddening line, of the detected stars from the theoretical curve (Bertelli et al. 1994) is a measure of the color excess. Dividing the images with a superimposed spatial grid we can count stars in each box and then estimate the extintion with respect to an external reference region. Estimating the extinction and its dispersion we can plot these two quantities obtaining an almost linear behaviour that steepens at decreasing spatial resolution.This kind of behaviour has been also observed by Lada et al. (1994) and discussed by Padoan et al. (1997) in the context of a turbulent model. Extinction

  4. 4/5 Near-IR range (JHK) The extinction is obtained for the stars falling between the two reddening vectors delimiting a reddened region in the J-H vs H-K two-color diagram… …by considering the stars in each box of a superimposed grid we evaluate an average extinction for each position and then derive iso-extinction contours.

  5. 5/5 Conclusions By combining optical and near-IR imaging of dark nebulae we obtain a better mapping of the extinction: the optical range is better suited to map boundary regions (low column density), while in the near-IR range we better observe the extinction in the inner regions. This observational approach allows us to study the spatial behaviour of important parameters, such as Av and Rv, related to the dust column density and the mean grain size respectively.

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