R. Launhardt
Caltech Pasadena
Th. Henning
AIU Jena
P. Hofner
Arecibo
A. I. Sargent
Caltech Pasadena
CB 17 (L 1389) is a small, relatively isolated, simply structured
molcular cloud (Bok globule) located at a distance of ~ 300 pc.
The total mass of this small globule amounts to only a few
solar masses and its size (FWHM) is ~ 2.5' (~0.2 pc).
Measurements of different isotopes and transitions of
of CO, CS, HCO+, and H2CO toward the core of CB 17
have been obtained using the IRAM 30m and CSO 10.4m telescopes (Launhardt etal
1998, ApJS, 119, 59).
High-resolution measurements of the HCO+(1-0) transition
were performed with the OVRO millimetre wave array.
In addition, the submm and mm continuum emission was observed with the
JCMT 15m and IRAM 30m telescopes (Launhardt & Henning 1997, A&A, 326,
329;
Launhardt etal 1997, MNRAS, 288, L45).
These measurements reveal the presence of a central dense core of
~0.5M
(Launhardt etal 1999, in prep.). Although the
properties of this core resemble mostly those of a
pre-stellar core (Ward-Thompson etal 1994, MNRAS, 268, 276),
spectral signatures of
mass infall suggest that the protostellar collapse has already
started. Microturbulent radiative transfer calculations and dust
models are used to constrain the
kinematic state and physical conditions of this star-forming
globule core.