A schematic of the observed molecular emission and the physical components of the embedded protostellar system TMC1A. For the references given in the illustration, ‘et al.’ is abbreviated as “+”. References: Bjerkeli et al. (2016), Harsono et al. (2018), van ’t Hoff et al. (2020). Main panel: molecular gas components projected in the same way as in the observation. Inset at bottom right: interpretation of relative location of the origin of molecular gas emission shown in the (x, z) plane, with z along the rotation axis of the disk.