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 mu m 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 (CO)-C-12(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 x 10(4) yr. The WR star displays some cyclic variability. The mass computed for the WR60-6 nebula indicates that thematerial 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.