Low-density ionized interstellar gas as revealed by interstellar optical and H I radio lines

Abstract

view Abstract Citations (7) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Low-Density Ionized Interstellar Gas as Revealed by Interstellar Optical and H i Radio Lines Heiles, C. Abstract Stars showing nonzero velocity optical interstellar lines usually have no corresponding H I radio line, but there often exists an H I cloud at the same velocity 5 -10 away in the sky. We suggest that in many cases the radio line is unobservable at the position of the star because the gas is ionized. This ionization might be caused by a global source of ionization rather than a more localized one such as the star itself because there may be a tendency for such stars to exist almost exclusively at negative Galactic latitudes. Existing spectra of extragalactic objects should, in some cases, have sufficient velocity resolution to apply to these problems. Subject headings: interstellar matter - 21-centimeter radiation Publication: The Astrophysical Journal Pub Date: October 1974 DOI: 10.1086/181624 Bibcode: 1974ApJ...193L..31H Keywords: Atomic Spectra; Hydrogen Atoms; Interstellar Gas; Ionized Gases; Radio Spectra; Absorption Spectra; Astronomical Spectroscopy; Gas Density; Hydrogen Clouds; Hydrogen Ions; Line Spectra; Radio Astronomy; Astrophysics full text sources ADS | data products SIMBAD (6)