We present a detailed theoretical study of the isolated Bok globule CB17 ( L1389 ) based on spectral maps of CS , HCO ^ { + } , C ^ { 18 } O , C ^ { 34 } S , and H ^ { 13 } CO ^ { + } lines .
A phenomenological model of prestellar core evolution , a time-dependent chemical model , and a radiative transfer simulation for molecular lines are combined to reconstruct the chemical and kinematical structure of this core .
In addition we investigate the influence of various physical factors on molecular line profiles .
It is shown that the intensity of the external UV field , the probability for molecules to stick onto dust grains , the core age , and the rotation velocity all significantly affect the molecular line spectra .
Due to this influence , the asymmetry of optically thick lines allows to remove the ambiguity between the sticking probability and the core age .
We demonstrate that these parameters are well constrained , when results of the modeling are compared to observations in multiple lines of sight through the core .
We developed a general criterion that allows to quantify the difference between observed and simulated spectral maps .
By minimizing this difference , we find that very high and very low values of the effective sticking probability S are not appropriate for the studied prestellar core .
The most probable S value for CB17 is 0.3–0.5 .
The spatial distribution of the intensities and self-absorption features of optically thick lines is indicative of UV irradiation of the core .
By fitting simultaneously optically thin transitions of C ^ { 18 } O , H ^ { 13 } CO ^ { + } , and C ^ { 34 } S as well as optically thick transitions of HCO ^ { + } and CS , we isolate the model that reproduces all the available spectral maps to a reasonable accuracy and , thus , represents a good approximation to the core chemical and kinematical structure .
The line asymmetry pattern in CB17 is reproduced by a combination of infall , rotation , and turbulent motions with velocities \sim 0.05 km s ^ { -1 } , \sim 0.1 km s ^ { -1 } , and \sim 0.1 km s ^ { -1 } , respectively .
These parameters corresponds to energy ratios E _ { rot } / E _ { grav } \approx 0.03 , E _ { therm } / E _ { grav } \approx 0.8 , and E _ { turb } / E _ { grav } \approx 0.05 ( the rotation parameters are determined for i = 90 ^ { \circ } ) .
The chemical age of the core is about 2 Myrs .
In particular , this is indicated by the central depletion of CO , CS , and HCO ^ { + } .
On the other hand , the depletion is not strong enough to show up in intensity maps as a ring-like pattern .
Based on the angular momentum value , we argue that the core is going to fragment , i.e. , to form a binary ( multiple ) star .