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Abstract: Observational data and theoretical calculations show that significantsmall-scale substructures are present in dark molecular clouds. Theseinhomogeneities can provide precious hints on the physical conditions insidethe clouds, but can also severely bias extinction measurements. We presentNICEST, a novel method to account and correct for inhomogeneities in molecularcloud extinction studies. The method, tested against numerical simulations,removes almost completely the biases introduced by sub-pixel structures and bythe contamination of foreground stars. We applied NICEST to 2MASS data of thePipe molecular complex. The map thereby obtained shows significantly higher upto 0.41 mag in A K extinction peaks than the standard NICER Lombardi et al.2001 map. This first application confirms that substructures in nearbymolecular clouds, if not accounted for, can significantly bias extinctionmeasurements in regions with A K > 1 mag; the effect, moreover, is expected toincrease in more distant molecular cloud, because of the poorer physicalresolution achievable.



Author: Marco Lombardi

Source: https://arxiv.org/







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