We present results from a comprehensive submillimeter spectral survey toward the source Orion South , based on data obtained with the HIFI instrument aboard the Herschel Space Observatory , covering the frequency range 480 to 1900 GHz .
We detect 685 spectral lines with S/N > 3 \sigma , originating from 52 different molecular and atomic species .
We model each of the detected species assuming conditions of Local Thermodynamic Equilibrium .
This analysis provides an estimate of the physical conditions of Orion South ( column density , temperature , source size , & V _ { LSR } ) .
We find evidence for three different cloud components : a cool ( T _ { ex } \sim 20 - 40 K ) , spatially extended ( > 60 ^ { \prime \prime } ) , and quiescent ( \Delta V _ { FWHM } \sim 4 km s ^ { -1 } ) component ; a warmer ( T _ { ex } \sim 80 - 100 K ) , less spatially extended ( \sim 30 ^ { \prime \prime } ) , and dynamic ( \Delta V _ { FWHM } \sim 8 km s ^ { -1 } ) component , which is likely affected by embedded outflows ; and a kinematically distinct region ( T _ { ex } > 100 K ; V _ { LSR } \sim 8 km s ^ { -1 } ) , dominated by emission from species which trace ultraviolet irradiation , likely at the surface of the cloud .
We find little evidence for the existence of a chemically distinct “ hot core ” component , likely due to the small filling factor of the hot core or hot cores within the Herschel beam .
We find that the chemical composition of the gas in the cooler , quiescent component of Orion South more closely resembles that of the quiescent ridge in Orion-KL .
The gas in the warmer , dynamic component , however , more closely resembles that of the Compact Ridge and Plateau regions of Orion-KL , suggesting that higher temperatures and shocks also have an influence on the overall chemistry of Orion South .