Do the Infrared Emission Features Need Ultraviolet Excitation?
K. I. Uchida, K. Sellgren, M. Werner;
ApJ, 1998, 493, L109
ABSTRACT:We present the results of imaging spectroscopy of the reflection nebula vdB 133, obtained with the infrared camera and circular variable
filter wheel on the Infrared Space Observatory.
Our observations reveal the
infrared emission features (IEFs), at 6.2, 7.7, 8.7, 11.3, and 12.7 mu {m} , and
associated 5-15 mu m continuum emission.
The stellar system illuminating vdB 133
has the lowest ratio of ultraviolet (shortward of 0.4 mu m) to total flux of
any stars demonstrated to date to excite the IEFs and associated continuum
emission from adjacent interstellar dust, as opposed to circumstellar
dust.
The low fraction of UV flux from this system poses a problem for existing
models for the emission mechanism and emitting material, which all require
substantial UV radiation for the excitation of the IEFs and associated continuum.
KEYWORDS: infrared: ism: lines and bands, ism: dust, extinction, ism: individual alphanumeric: vdb 133, ism: molecules, ism: reflection nebulae, stars: individual henry draper number: hd 195593
PERSOKEY:dust, pah, iso, mir, reflection nebula, ,
CODE: uchida98