Disks around hot stars in the Trifid nebula

Abstract

We report on mid-IR observations of the central region in the Trifid nebula, carried out with ISOCAM in several broad-band infrared filters and in the low resolution spectroscopic mode provided by the circular variable filter. Analysis of the emission indicates the presence of a hot dust component (500 to 1000 K) and a warm dust component at lower temperatures (~ 150-200 K) around several members of the cluster exciting the H II region, and other stars undetected at optical wavelengths. Complementary VLA observations suggest that the mid-IR emission could arise from a dust cocoon or a circumstellar disk, evaporated under the ionization of the central source and the exciting star of the nebula. In several sources the 9.7 kern 0.20em mu m silicate band is seen in emission. One young stellar source shows indications of crystalline silicates in the circumstellar dust.