Mid-Infrared Emission Features in WL 16

Open Access
Publisher Website
Google Scholar
Abstract
We present long-slit 7.5-13.5 μm spectra of WL 16, a Herbig Ae star in the ρ Ophiuchi dark cloud that is surrounded by a ~1000 AU diameter infrared-emitting nebula. Mid-IR emission features are detected in every region of the nebula from center to edge, and the underlying continuum color temperature is approximately 10 times hotter than would be expected from large grains in thermal equilibrium. The 7.7 and 8.6 μm features decrease in intensity more rapidly with distance from the central star than the 11.3 and 12.7 μm features, suggesting that PAH ionization effects proposed to explain similar spectral variations in other ISM sources may be important in WL 16 as well.