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Paper: Identification of Main Sequence Stars with Mid-Infrared Excesses Using GLIMPSE
Volume: 357, The Spitzer Space Telescope: New Views of the Cosmos
Page: 124
Authors: Uzpen, B.; Kobulnicky, H.A.; Clemens, D.P.; Whitney, B.A.
Abstract: Spitzer IRAC 3.6-8 μm 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 RCW49. These stars comprise a subset of 184 stars with known spectral classifications, 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 are main-sequence stars. Modeling the excesses as blackbodies demonstrates that the blackbody components have fractional bolometric disk-to-star luminosity ratios, LIR/L* , ranging from 10−3 to 10−2 with temperatures ranging from 220 K to 820 K. Five of the 33 stars are O or B stars with excesses that can be plausibly explained by thermal bremsstrahlung emission, and four are post main-sequence stars. Of the remaining 24 main-sequence stars, 18 have SEDs that are consistent with hot dusty debris disks, a possible signature of planet formation. 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 K.
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