| Description |
We propose to investigate the interstellar chemistry and physics of nitrogen
through Herschel/HIFI observations of simple nitrogen-hydride molecules
including 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 comparison
can 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 different
parts 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. |
