SPECTRAL SURVEY OF THE STAR FORMATION REGION DR21OH IN THE 4-mm WAVELENGTH RANGE

The results of a spectral survey of the star-forming region DR21OH in the 4 mm wavelength range are presented. Sixty-nine molecules and their isotopologues have been detected, ranging from simple diatomic or triatomic molecules, such as SO, SiO and CCH, to complex organic species, such as CH₃OCHO or CH₃OCH₃. A noТаблица part of the results qualitatively repeat the results of the survey of the same source at 3 mm. The inventories of molecules found at 3 and 4 mm overlap to a great extent. However, at 4 mm we found a number of species that have no allowed transitions in the 3 mm wavelength range, e.g. DCN, DNC, or SO⁺. The bulk of the molecules detected at 4 mm are those that are common for dense cores, e.g., HC₃N or CH₃CCH, but some of the detected molecules are typical for hot cores. The latter include complex organic molecules CH₃OCHO, CH₃CH₂OH, CH₃OCH₃, etc. However, the detected emission of these molecules probably arise in a gas heated to 30 K only. Nine molecules, including complex species CH₃C₃N, CH₃CH₂CN, CH₃COCH₃, were found by spectral line stacking. This demonstrates the prospects of the method for the study of molecular clouds.