2021MNRAS.501..347A

Recent observations indicate that organic molecules are prevalent towards starless and pre-stellar cores. Deuteration of these molecules has not been well studied during the starless phase. Published observations of singly deuterated methanol, CH₂DOH, have only been observed in a couple of well-studied, dense, and evolved pre-stellar cores (e.g. L1544, L183). Since the formation of gas-phase methanol during this cold phase is believed to occur via desorption from the icy grain surfaces, observations of CH₂DOH may be useful as a probe of the deuterium fraction in the ice mantles of dust grains. We present a systematic survey of CH₂DOH towards 12 starless and pre-stellar cores in the B10 region of the Taurus molecular cloud. Nine of the 12 cores are detected with [CH₂DOH]/[CH₃OH] ranging from <0.04 to 0.23^+0.12_–0.06 with a median value of 0.11. Sources not detected tend to have larger virial parameters and larger methanol linewidths than detected sources. The results of this survey indicate that deuterium fractionation of organic molecules, such as methanol, during the starless phase may be more easily detectable than previously thought.