EDP Sciences
Free Access
Volume 438, Number 1, July IV 2005
Page(s) 169 - 185
Section Interstellar and circumstellar matter
DOI https://doi.org/10.1051/0004-6361:20042267
Published online 06 July 2005

A&A 438, 169-185 (2005)
DOI: 10.1051/0004-6361:20042267

Optimal column density measurements from multiband near-infrared observations

M. Lombardi1, 2

1  European Southern Observatory, Karl-Schwarzschild-Straße 2, 85748 Garching bei München, Germany
    e-mail: mlombard@eso.org
2  University of Milan, Department of Physics, via Celoria 16, 20133 Milan, Italy

(Received 27 October 2004 / Accepted 22 March 2005)

We consider from a general point of view the problem of determining the extinction in dense molecular clouds. We use a rigorous statistical approach to characterize the properties of the most widely used optical and infrared techniques, namely the star count and the color excess methods. We propose a new maximum-likelihood method that takes advantage of both star counts and star colors to provide an optimal estimate of the extinction. Detailed numerical simulations show that our method performs optimally under a wide range of conditions and, in particular, is significantly superior to the standard techniques for clouds with high column-densities and affected by contamination by foreground stars.

Key words: dust, extinction -- methods: statistical -- ISM: clouds -- infrared: ISM -- stars: formation

© ESO 2005

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.