• Hankins, Matthew
• Lau, Ryan M.
• Morris, Mark
• Adams, Joseph D.
• Herter, Terry L.

Abstract

We present SOFIA/FORCAST observations of the Quintuplet Proper Members (QPMs) at 19.7, 31.5, and 37.1 μm, and revisit our dust models of their spectral energy distribution (SEDs) using the radiative transfer code DUSTY. We fit the SED models with parameters reflecting the dust distribution arising from colliding wind binaries, which produce the 'pinwheels' previously observed in the near-infrared. Our models use amorphous carbon grains which are consistent with the dusty WC star hypothesis. The positive radial density profile that we fit is consistent with the majority of the dust mass being located away from the site of grain formation. However, the observed spiral/disk geometry is at odds with the large observed IR luminosity, ~10<SUP>5</SUP> L<SUB>sun</SUB>, which is comparable to the luminosity of typical WC stars, implying that the source must be completely enshrouded by dust. This is consistent with the obscuration of J-band features noted in other works. The small observed dust mass, ~10<SUP>-4</SUP>-10<SUP>-5</SUP> M<SUB>sun</SUB>, is consistent with inefficient grain formation or low survivability. Our images provide important spectral information as they are sensitive to cool dust components that are independent of the previously observed hot inner disk. Ultimately these objects remain somewhat of an enigma due to their low observed dust mass and the conflict between the spiral dust morphology and the reradiated luminosity.

Topics

• density
• impedance spectroscopy
• amorphous
• Carbon
• grain