Spitzer/IRAC-MIPS survey of NGC 2244:: Protostellar disk survival in the vicinity of hot stars

We present the results from a survey of NGC 2244 from 3.6 to 24 mu m with the Spitzer Space Telescope. The 24 mu m- 8 mu m-3.6 mu m color composite image of the region shows that the central cavity surrounding the multiple O and B stars of NGC 2244 contains a large amount of cool dust visible only at 24 mu m. Our survey gives a detailed look at disk survivability within the hot-star-dominated environment in this cavity. Using mid-infrared two-color diagrams ( [ 3: 6 ]- [4. 5] vs. [5. 8] - [8.0]), we identified 337 class II and 25 class I objects out of 1084 objects detected in all four of these bands with photometric uncertainty better than 10%. Including the 24 -m data, we found 213 class II and 20 class I sources out of 279 stars also detected at this latter band. The center of the class II density contours is in very good agreement with the center of the cluster detected in the 2MASS images. We studied the distribution of the class II sources relative to the O stars and found that the effect of high-mass stars on the circumstellar disks is significant only in their immediate vicinity.