2019ApJ...880..138H

IRAM 30 m Observations toward eight protostellar outflow sources were taken in the 96-176 GHz range. Transitions of CH₃OH and CH₃CHO were detected in seven of them. The integrated emissions of the transitions of each species that fell into the observed frequency range were measured and fit using RADEX and LTE models. Column densities and gas properties inferred from this fitting are presented. The ratio of the A and E-type isomers of CH₃OH indicates that the methanol observed in these outflows was formed on the grain surface. Both species demonstrate a reduction of terminal velocity in their line profiles in faster outflows, indicating destruction in the post-shock gas phase. This destruction, and a near constant ratio of the CH₃OH and CH₃CHO column densities, imply it is most likely that CH₃CHO also forms on the grain surface.