the submillimeter emission results. Moreover, beyond a radius of $\sim 5000-10000$ AU, the typical column density profile steepens with distance from core center and gets steeper than $N_{H_{2}} \propto \bar{r}^{-1}$, until it eventually merges with the low-density ambient molecular cloud. At least three of the cores present sharp edges at $R \sim 15000-30000$ AU and appear to be decoupled from their parent clouds, providing finite reservoirs of mass for subsequent star formation.'
author:
- 'A. Bacmann$^{1}$[^1], P. André$^{1}$[^2], J.-L. Puget$^{2}$, A. Abergel$^{2}$, S. Bontemps$^{3}$, D. Ward-Thompson$^{4}$'
date: 'Received 28 October 1999 / accepted 8 March 2000'
title: 'An ISOCAM absorption survey of the structure of pre-stellar cloud cores[^3]'
---

Introduction
============

Although our general understanding of low-mass star formation has made significant theoretical and observational progress in the past three decades (see, e.g., the volumes by Levy & Lunine 1993 and Mannings, Boss, & Russell 2000 for comprehensive reviews), the earliest stages of the star formation process remain poorly known. These stages immediately preceding and immediately following the onset of protostellar collapse are of great interest since to some extent they must govern the origin of stellar masses, i.e., the stellar initial mass function.

According to present ideas on isolated 