Since their discovery , the Quintuplet proper members ( QPMs ) have been somewhat mysterious in nature .
Originally dubbed the “ cocoon stars ” due to their cool featureless spectra , high-resolution near-infrared imaging observations have shown that at least two of the objects exhibit “ pinwheel ” nebulae consistent with binary systems with a carbon-rich Wolf-Rayet star and O/B companion .
In this paper , we present 19.7 , 25.2 , 31.5 , and 37.1 \mu m observations of the QPMs ( with an angular resolution of 3.2-3.8 ” ) taken with the Faint Object Infrared Camera for the SOFIA Telescope ( FORCAST ) in conjunction with high-resolution ( \sim 0.1-0.2 ” ) images at 8.8 and 11.7 \mu m from the Thermal-Region Camera Spectrograph ( TReCS ) .
DUSTY models of the thermal dust emission of two of the four detected QPMs , Q2 and Q3 , are fitted by radial density profiles which are consistent with constant mass loss rates ( \rho _ { d } \propto r ^ { -2 } ) .
For the two remaining sources , Q1 and Q9 , extended structures ( \sim 1 " ) are detected around these objects in high-resolution imaging data .
Based on the fitted dust masses , Q9 has an unusually large dust reservoir ( \mathrm { M _ { d } } = 1.3 ^ { +0.8 } _ { -0.4 } \times 10 ^ { -3 } \mathrm { M _ { \odot } } ) compared to typical dusty Wolf-Rayet stars which suggests that it may have recently undergone an episode of enhanced mass loss .