2012MNRAS.422.1098R

We present a multi-wavelength observational study towards the high-mass young stellar object G8.68-0.37. A single massive gas-and-dust core is observed in the (sub)millimetre continuum and molecular line emissions. We fitted the spectral energy distribution (SED) from the dust continuum emission. The best-fitting SED suggests the presence of two components with temperature of T_d= 20 and 120 K, respectively. The core has a total mass of up to 1.5 {x} 10³ M_☉ and a bolometric luminosity of 2.3 {x} 10⁴ L_☉. Both the mass and luminosity are dominated by the cold component (T_d= 20 K). The molecular lines of C¹⁸O, C³⁴S, DCN and thermally excited CH₃OH are detected in this core. Prominent infall signatures are observed in the ¹²CO (1 - 0) and (2 - 1). We estimated an infall velocity of 0.45 km/s and a mass infall rate of 7 {x} 10^–4 M_☉/yr. From the molecular lines, we have found a high DCN-to-HCN abundance ratio of 0.07. The overabundant DCN may originate from a significant deuteration in the previous cold pre-protostellar phase. And the DCN should now be rapidly sublimated from the grain mantles to maintain the overabundance in the gas phase.