Further studies of ionization in interstellar clouds

Abstract

view Abstract Citations (71) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Further studies of ionization in interstellar clouds. Hobbs, L. M. Abstract Interferometric scans of the interstellar 7699-A line of K I or of the D1 line of Na I are reported for 14 stars. Along with results obtained recently by others for the column densities of H I, H2, or Na I toward a larger number of stars, these results are added to a previous compilation of such data, and are used to reanalyze the relations among the well-correlated K I, Na I, and total hydrogen column densities. The estimated depletion factors of both K and Na are about 3 to 4. Alternatively, the fractional ionization will be at least 0.0009 in these relatively low-density clouds if the K and Na abundances are not to exceed their solar values. Photoionization of the heavy elements by starlight can account for the greater part of this ionization if interstellar carbon is undepleted. The influence of temperature effects and of gas-phase chemical reactions on the approximately quadratic variations of the K I and Na I column densities with the total hydrogen column density is discussed. Publication: The Astrophysical Journal Pub Date: January 1976 DOI: 10.1086/154056 Bibcode: 1976ApJ...203..143H Keywords: Abundance; Astronomical Spectroscopy; Cosmic Rays; Gas Ionization; Hydrogen Clouds; Interstellar Gas; Gas Density; Graphs (Charts); Interferometry; Line Spectra; Photoionization; Potassium; Recombination Coefficient; Sodium; Astrophysics full text sources ADS | data products SIMBAD (33)