2019AJ....157...20O

We present a (sub)millimeter line survey of the methanol maser outflow located in the massive star-forming region DR21(OH) carried out with the Submillimeter Array (SMA) at 217/227 GHz and 337/347 GHz. We find transitions from several molecules toward the maser outflow such as CH₃OH, H₂CS, C¹⁷O, H¹³CO⁺, and C³⁴S. However, with the present observations, we cannot discard the possibility that some of the observed species such as C¹⁷O, C³⁴S, and H₂CS, might be instead associated with the compact and dusty continuum sources located in the MM2 region. Given that most of transitions correspond to methanol lines, we have computed a rotational diagram with CASSIS and an LTE synthetic spectra with XCLASS for the detected methanol lines in order to estimate the rotational temperature and column density in the small solid angle of the outflow where enough lines are present. We obtain a rotational temperature of 28 ± 2.5 K and a column density of 6.0 ± 0.9 x 10¹⁵ cm^–2. These values are comparable to those column densities/rotational temperatures reported in outflows emanating from low-mass stars. Extreme and moderate physical conditions to excite the maser and thermal emission coexist within the CH₃OH flow. Finally, we do not detect any complex molecules associated with the flow, e.g., CH₃OCHO, (CH₃)₂CO, and CH₃CH₂CN.