| Description |
We propose to investigate the interstellar chemistry and physics of nitrogenthrough Herschel/HIFI observations of simple nitrogen-hydride moleculesincluding NH, NH2, NH3, and related ions. The nitrogen chemistry is still rather uncertain and we therefore propose to compare and contrast the abundances and ortho/para ratios of nitrogen hydrides in the diffuse interstellar gas to the dense cores of molecular clouds. This comparisoncan be done very efficiently by observing excited-state transitions in selected cores that have previously been used in the PRISMAS program as background sources for absorption measurements in the ground-state transitions. In this way, we will determine whether nitrogen chemistry is dominated by gas-phase reactions or by processes on surfaces of dust grains, and whether the dominant chemistry is different in differentparts of the interstellar medium. In summary, we propose HIFI observations of 5 transitions of simple nitrogen-bearing molecules in 8 sources, and 3 transitions in 2 sources. The total requested observing time is 26.2 hours. |
