We combine spectra of VY CMa obtained with the short- and long-wavelength spectrometers , SWS and LWS , on the Infrared Space Observatory to provide a first detailed continuum spectrum of this highly luminous star .
The circumstellar dust cloud through which the star is observed is partially self-absorbing , which makes for complex computational modeling .
We review previous work and comment on the range of uncertainties about the physical traits and mineralogical composition of the modeled disk .
We show that these uncertainties significantly affect the modeling of the outflow and the estimated mass loss .
In particular , we demonstrate that a variety of quite diverse models can produce good fits to the observed spectrum .
If the outflow is steady , and the radiative repulsion on the dust cloud dominates the star ’ s gravitational attraction , we show that the total dust mass-loss rate is \sim 4 \times 10 ^ { -6 } M _ { \odot } yr ^ { -1 } , assuming that the star is at a distance of 1.5 kpc .
Several indications , however , suggest that the outflow from the star may be spasmodic .
We discuss this and other problems facing the construction of a physically coherent model of the dust cloud and a realistic mass-loss analysis .