| Description |
The HIFI instrument on Herschel provides a unique opportunity to undertake an astronomical study of light negative molecular ions in the interstellar gas, as these are difficult or impossible to observe from ground based observatories. A sensitive search for the negative ions CN-, CCH-, and OH- with HIFI toward 6 galactic molecular sources is proposed. Three successive rotational transitions (J=6, 7, 8) of CN- and CCH- in HIFI bands 1 - 3, and the lowest rotational transition of OH- near 1.12 THz will be observed. The goals of this study are: i. to enlarge the number of known sources of light negative molecular ions; ii. to determine the abundances of the anions, as well as the anion-to-neutral ratios to assess theoretical models of the fractional ionization of molecular clouds; and iii. to assess the chemical environment of anions through parallel observations of neutral molecules (H13CN and HNC) and positive molecular ions (CO+ and H13CO). |
