ISO far infrared observations of the high latitude cloud L 1642. I. The density and temperature structure

Abstract

We have performed a large-scale mapping of the high-latitude, moderate extinction dark cloud L 1642 with ISO (Infrared Space Observatory) at 200 μm to study the properties of dust, the virial equilibrium condition of the cloud, and their relation to star formation. The cloud consists of three denser regions which are connected by diffuse material. Only one of the regions, the one most massive and with the greatest optical depth, is related to a temperature mimimum. The pre-main sequence binary stars IRAS 04325-1419 and IRAS 04327-1419, probably born within the cloud, are located close to this temperature mimimum coinciding with the column density maximum. The minimum dust temperature is ∼13.8 K. The ratio 2E_kin/|E_pot| for the star-forming region is about 1.2, and thus it is close to being gravitationally bound. However, the other regions are not gravitationally bound. On a 1 arcmin-10 arcmin spatial scale the radial density distributions, derived from far-infared optical depth maps, are similar between the star-forming and non star-forming regions. The differences that distinguish the star-forming core appear to be its higher density and lower dust temperature.

Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, The Netherlands and the United Kingdom) and with the participation of ISAS and NASA.