We thank Peter Hofner for supplying the 7 mm continuum flux plotted in Fig. 7 and Qizhou Zhang for providing us with the NH3(1,1) data presented in Fig. 15. Many thanks are also due to Tom Herbst for his help during the UKIRT observations, to Jerry Acord for making us available the SiO(2-1) and H13CO+(1-0) spectra acquired by him with the 30-m radio telescope, and to Debra Shepherd for useful discussions. LT was partially supported by NASA's Origins of the Solar System program (grant NAGW-4030). This project was also partially supported by ASI grants ARS-96-66 and ARS-98-116 to the Osservatorio Astrofisico di Arcetri.
© European Southern Observatory (ESO) 1999
Online publication: April 28, 1999