2005/06/22 by Gai I. Boger, A. Sternberg, Amiel Sternberg · 5 citations
Chemistry · Earth and Planetary Sciences · Physics and Astronomy · #Astrophysics and Star Formation Studies #Atmospheric Ozone and Climate #Spectroscopy and Laser Applications #astro-ph
paper · pdf · doi:10.1086/432864
published as Astrophys.J.632:302-315,2005 · Accepted for publication in ApJ, 33 pages, 8 figures
arxiv created 2005/06/22 · openalex publication_date 2005/10/03 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a theoretical investigation of CN and HCN molecule formation in dense interstellar clouds. We study the gas-phase CN and HCN production efficiencies from the outer photon-dominated regions (PDRs) into the opaque cosmic-ray-dominated cores. We calculate the equilibrium densities of CN and HCN and of the associated species C + , C, and CO, as functions of the far-ultraviolet (FUV) optical depth. We consider isothermal gas at 50 K, with hydrogen particle densities from 10 2 to 10 6 cm -3 . We study clouds that are exposed to FUV fields with intensities (at 1000 Å) from 1 × 10 -18 to 1 × 10 -14 ergs s -1 cm -2 Hz -1 sr -1 , or 20 to 2 × 10 5 times the mean interstellar FUV intensity. We assume cosmic-ray H 2 ionization rates ranging from 5 × 10 -17 s -1 to an enhanced value of 5 × 10 -16 s -1 . We also examine the sensitivity of the density profiles to the gas-phase sulfur abundance.