A search for co-evolving ion and neutral gas species in prestellar   molecular cloud cores
  Comparison of linewidths of spectral line profiles of ions and neutral molecules have been recently used to estimate the strength of the magnetic field in turbulent star-forming regions. However, the ion (HCO+) and neutral (HCN) species used in such studies may not be necessarily co-evolving at every scale and density and may thus not trace the same regions. Here, we use coupled chemical/dynamical models of evolving prestellar molecular cloud cores including non-equilibrium chemistry, with and without magnetic fields, to study the spatial distribution of HCO+ and HCN, which have been used in observations of spectral linewidth differences to date. In addition, we seek new ion-neutral pairs that are good candidates for such observations because they have similar evolution and are approximately co-spatial in our models. We identify three such good candidate pairs: HCO+/NO, HCO+/CO, and NO+/NO. 
Konstantinos Tassis (MPIfR), Talayeh Hezareh (MPIfR), and Karen   Willacy (JPL)
astro-ph.GA