Analysis of spatial temperature variations in regions of massive star formation

Abstract

Using the 20-m Onsala Observatory telescope (Sweden), we performed observations of the CH3C2H(6-5) line toward several regions of massive star formation to estimate the kinetic temperature of the gas and study its variations over the sources. Intense lines were detected in five objects. For these, we estimated the kinetic temperature of the gas near the CS and N2H+ molecular emission peaks by the method of population diagrams. A significant temperature difference between these peaks is noticeable only in W3 and, to a lesser degree, in DR 21. In the remaining cases, it is insignificant. This indicates that the chemical differentiation of the molecules in these regions cannot be associated with temperature variations. The kinetic temperature determined from methyl acetylene observations is usually slightly higher than the temperature estimated from ammonia observations. This is probably because the methyl acetylene emission originates in denser, i.e., deeper and hotter layers of the cloud.