Methanol and other molecular tracers of outflows and dense gas in the molecular cloud G345.01+1.79

Abstract

The results of SEST millimeter observations of the molecular cloud G345.01+1.79 are presented. Spectra of CH3OH, SO2, SiO, HCO+, C18O, C33S, C34S, HCN, and DCN lines have been obtained. Mapping of the cloud in CH3OH, SiO, and C34S lines indicates that the maximum integrated intensity in the SiO and C34S lines and in low-excitation CH3OH transitions coincide with the northern group of methanol masers, while the corresponding maximum for high-excitation CH3OH transitions coincides with the southern methanol-maser group. The physical parameters are estimated from the quasi-thermal CH3OH lines under the large-velocity-gradient approximation, and their distribution on the sky derived. The density and temperature are higher toward the southern group of methanol masers than in the northern group. This may indicate that star formation is in an earlier stage of evolution in the northern than toward the southern group. A maser component can be distinguished in 14 (of 71) CH3OH lines. We have detected for the first time weak, probably maser, emission in the CH3OH lines at 148.11, 231.28, 165.05, 165.06, and 165.07 GHz. A blue wing is clearly visible in the CH3OH, SiO, C18O, and SO2 lines. The emission in this wing is probably associated with a compact source whose velocity is characteristic of the CH3OH maser emission in the southern group of masers.