| Description |
we intend to examine the massive star formation region ngc 6334 in the near- and mid-infrared in order to investigate the dust properties at each of 8 sites of massive star formation in the cloud: ngc 6334 a, c, d, e, f, v, i(n) and g351.20+0.70. by making sws full-grating scans toward each site of massive star formation and examining the fine-structure lines from ionic species, we will determine the hardnesses of the uv fields, and thus derive the zams spectral types. to determine the gas density and uv field strength based on pdr models, we will use the [si ii] 35um line, along with the [c ii] 158um and [o i] 145um lines from our previously observed iso lws full-grating scans. because the [o i] 63um is anomalously faint toward at least two of the sources in ngc 6334, probably due to self-absorption, the optically thin [s ii] 35um line is essential for testing the model predictions. we will investigate the dependence on the hardness of the uv field of the uir features at 6.3, 7.7, 8.6 and 11.3um. we will also examine the relative strength of ice vs. silicate features and their dependence on the hardness of the uv field. we will also image each site with isocam through 4 settings of the cvf filter. because the sources are so bright, we need the cvf filter to avoid saturation. by imaging the well-isolated 6.3um uir feature at each site, we will determine the survivability of small grains in hard/intense uv fields. in order to separate the uir feature from the continuum emission, we will take images at 5.8 and 6.8um. these continuum images, plus the fourth cvf filter setting at 14.8um, will allow us to determine the dust opacity, a crucial input parameter for pdr models. |
