Spitzer IRAC 3.6-8 \mu m photometry obtained as part of the GLIMPSE survey has revealed mid-infrared excesses for 33 field stars with known spectral types in a 1.2 sq .
degree field centered on the southern Galactic H ii region RCW 49 .
These stars comprise a subset of 184 stars with known spectral classification , most of which were pre-selected to have unusually red IR colors .
We propose that the mid-IR excesses are caused by circumstellar dust disks that are either very late remnants of stellar formation or debris disks generated by planet formation .
Of these 33 stars , 29 appear to be main-sequence stars based on optical spectral classifications .
Five of the 29 main-sequence stars are O or B stars with excesses that can be plausibly explained by thermal bremsstrahlung emission , and four are post main-sequence stars .
The lone O star is an O4V ( ( f ) ) at a spectrophotometric distance of 3233 ^ { +540 } _ { -535 } pc and may be the earliest member of the Westerlund 2 cluster .
Of the remaining 24 main-sequence stars , 18 have SEDs that are consistent with hot dusty debris disks , a possible signature of planet formation .
Modeling the excesses as blackbodies demonstrates that the blackbody components have fractional bolometric disk-to-star luminosity ratios , \frac { L _ { IR } } { L _ { * } } , ranging from 10 ^ { -3 } to 10 ^ { -2 } with temperatures ranging from 220 to 820 K. The inferred temperatures are more consistent with asteroid belts rather than the cooler temperatures expected for Kuiper belts .
Mid-IR excesses are found in all spectral types from late B to early K .