Detached dust shell around wolf-rayet star WR60-6 in the young stellar cluster VVV CL036

The discovery of a detached dust shell around the Wolf-Rayet (WR) star WR60-6 in the young stellar cluster VVV CL036 is reported. This shell is uncovered through the Spitzer-MIPS 24 μm image, where it appears brightest, and it is invisible at shorter wavelengths. Using new APEX observations and other data available from the literature, we have estimated some of the shell parameters: the inner and outer radii of 0.15 and 0.90 pc, respectively; the overall systemic velocity of the molecular ¹²CO(3 → 2) emission of -45.7 ± 2.3 km s^-1; an expansion velocity of the gas of 16.3 ± 1 km s^-1; the dust temperature and opacity of 122 ± 12 K and 1.04, respectively; and an age of 2.8 × 10⁴ yr. The WR star displays some cyclic variability. The mass computed for the WR60-6 nebula indicates that the material was probably ejected during its previous stages of evolution. In addition, we have identified a bright spot very close to the shell, which can be associated with the Midcourse Space Experiment source G312.13+00.20.