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T.L. Smith (Louisiana State University), K.D. Gordon (Steward Observatory), G.C. Clayton (Louisiana State University)
Recent work on Extended Red Emission (ERE) emitting filaments in the reflection nebula NGC 7023 has revealed the existence of two new broad dust emission features in the near-infrared. The feature detected at 1.5 \mum has been confirmed in subsequent observations of NGC 7023 and is attributed to \beta FeSi2. This would make the 1.5 \mum feature the first solid-state Fe feature seen from dust grains. There has been no confirmation of the feature at 1.15 \mum in NGC 7023, attributed to silicon nanoparticles. Confirmation of the existence of the 1.15 \mum emission feature is especially important with respect to the impact on the current debate on the carrier of Extended Red Emission (ERE), which has been attributed to both silicon nanoparticles and aromatic hydrocarbon clusters. ERE is a strong dust emission feature detectable in almost all dusty astrophysical environments with sufficient UV photons for excitation. Identifying the material responsible for producing ERE is important as its strength in the diffuse ISM has required the ERE carrier in dust to be a significant component of dust grains in general. Including NGC 7023, we observed four reflection nebulae using SPEX on the NASA infrared telescope facility (IRTF) and obtained long-slit spectrscopic data from 0.8 to 2.5 \mum. We present our attempts to confirm the 1.15 \mum feature in NGC 7023 and to find the 1.5 \mum feature in other filaments in NGC 7023 and in other reflection nebulae.
The author(s) of this abstract have provided an email address for comments about the abstract: tsmith@dirty.phys.lsu.edu