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Session 15 - Interstellar Medium I.
Display session, Monday, January 15
North Banquet Hall, Convention Center

[15.02] Investigation Of Infrared Colors Around Early Type Stars

S. J. Carey, R. F. Shipman, F. O. Clark (Phillips Laboratory/GPOB)

In order to determine the affect of the radiation field of an early type star upon the ambient interstellar medium, we have investigated the infrared colors of interstellar dust surrounding 7 stars with spectral types ranging between B1 to B7. The infrared colors (at 12 \: \mu m / 100 \: \mu m, 25 \: \mu m /100 \: \mu m, 60 \: \mu m /100 \: \mu m and 12 \: \mu m /25 \: \mu m) of our sources have been determined from the co-added ISSA data product. Four of the sources exhibit a marked increase in the 60/100 color towards the embedded object. The colors of the remaining sources are indistinguishable from nearby infrared cirrus. The most obvious explanation of the increase is heating by the embedded star. Associated with the 60/100 increase is a corresponding decrease in the 12/100 and 25/100 colors. The 12/25 color exhibits more complicated behavior, increasing from the background cirrus color then decreasing closer to the embedded star. Physical models of the infrared colors incoporating grain destruction and non-equilibrium heating will be presented. The effects of the strength and hardness of the radiation field on the dust as a function of spectral type and distance from the star will be explored. This work was performed while S. J. Carey held a National Research Council - AFGL Research Associateship.

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