Observatory, Tahtitorninmaki, P.O. Box 14, 00014 University of Helsinki, Finland
We present far-infrared observations of the dark cloud DC303.8-14.2, located in the Chamaeleon dark cloud complex. In the center of the cloud is located an IRAS point source, which has a spectral energy distribution (SED) typical of a young embedded object (YSO), i.e. the SED rises sharply at long wavelenghts.
Lehtinen has observed this cloud in millimeter molecular lines, and found that some of the molecules (e.g. CS(J=1-0, J=3-2)) show line profiles which are typical for a collapsing cloud (Lehtinen 1997, AA 317, L5).
In a recent paper, Lehtinen & Higdon (1998, submitted to AA) have observed centimeter wavelength continuum radiation from the IRAS source. The detected emission is most probably thermal free-free emission from ionized gas around the YSO.
Based on other similar objects it is known that the SED peaks at far-IR
wavelengths, at much longer than 100
.
If we want to study the SED
and
luminosity of this object, we need observations at longer wavelengths than
provided by IRAS. In these deeply embedded objects, the dust around a YSO
absorbs almost all the UV, optical and near-IR radiation from a YSO, and
emits the radiation back in the form of thermal dust emission. The far-IR
measurements enable us to determine the temperature of dust, and thus
the total energy emitted at far-IR wavelengths by the whole dust cloud.
We have done a similar study for a dark cloud without star
formation (Lehtinen et al. 1998, AA 333, 702).
We have mapped an area of about
at 100 and 200.
At 60
we
have a narrower stripe through the IRAS source. The IRAS source is located
on a plateau of emission from cold dust. We hace estimated the temperature
of the cold dust surrounding the YSO, and the total amount of energy emitted
by dust as a thermal continuum emission.
By combining the IRAS, ISO and cm-wavelength continuum observations we can construct a rather complete SED for the IRAS source. We have used this SED to estimate the bolometric luminosity and temperature of the IRAS source. Finally, we have estimated the evolutionary stage of the YSO, i.e. is it a so called Class 0 or Class I object.