1996A&A...312..989P

We present ¹²CO, ¹³CO and C¹⁸O (J: 1->0) and (J: 2->1) observations of B 164. This large Bok globule (Bok & Cordwell 1973) is interesting because it is isolated, has a peculiar velocity profile and seems to have been recently compressed on its western side. Assuming that this globule was originally spherical and in rotation, we try to interpret the ¹³CO and C¹⁸O data with a Berne's (1978, 1979) type Monte-Carlo radiative transfer model in which we have introduced rotation. The best solution indicates a large envelope of outwards-decreasing density from 1000cm^–3 to 100cm^–3 and a relatively small core with central density of the order of 5000cm^–3. CO isotopomers have a very low abundance in this model with the ¹³CO abundance in the range 10^–7-3x10^–6 and C¹⁸O≃1-2x10^–8. Next, we show that if π¹ Cyg (Azelfafage, HD 206672), a Be3-III star is at the same distance as B 164 from us, it could be the progenitor of the observed compression. Using a chemico-hydro-dynamical (CHD) model (Breart de Boisanger et al. 1992) we show that the most probable explanation is that the star has just arrived close enough to the cloud to efficiently compress it via the heating of the diffuse interstellar medium and/or the increase in radiation pressure.