Starburst galaxies are powered by newly formed massive stars, and are heavily obscured by dust, prohibiting the UV and optical studies. A fine-structure line from Ne+ ion ([Ne II] 12.8 μm) is usually the brightest mid-infrared(MIR) line emitted from starburst galaxies. The [Ne II] line suffers from far less dust extinction than the optical line does, and hence it is often used as a probe for starburst properties of galaxies(Achtermann & Lacy, 1995; Roche et al., 1991). However, the [Ne II] line should not be used as the physical probe unless the relationship between Ne+ abundance and spectral type of the ionizing star is established for very dusty H II regions. To study this, we started the [Ne II] line survey toward dusty ultracompact(UC) H II regions in our Galaxy. The UC H II regions are powered by newly formed early-type stars whose spectral type can be inferred from their radio and far-infrared(FIR) properties.
A far-infrared molecular and atomic line survey of the Orion KL region
