| 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. |
| Publication |
Ortho-to-para ratio of NH2. Herschel-HIFI observations of ortho- and para-NH2 rotational transitions towards W31C, W49N, W51, and G34.3+0.1 . Persson C. M. et al. . Astronomy & Astrophysics, Volume 586, id.A128, 20 pp. . 586 . 10.1051/0004-6361/201526781 . 2016A&A...586A.128P ,
Herschel Survey of Galactic OH+, H2O+, and H3O+: Probing the Molecular Hydrogen Fraction and Cosmic-Ray Ionization Rate . Indriolo Nick et al. . The Astrophysical Journal, Volume 800, Issue 1, article id. 40, 26 pp. (2015). . 800 . 10.1088/0004-637X/800/1/40 . 2015ApJ...800...40I ,
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