A view of the galactic H-alpha background - L = 208-218 deg, B = -2 to +8 deg

Abstract

view Abstract Citations (48) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A View of the Galactic H alpha Background: 208 degrees <=l <=218 degrees ; -2 degrees <=b <= +8 Reynolds, R. J. Abstract Faint, diffuse H-alpha emission from the interstellar medium has been mapped at 1-deg angular resolution and 12 km/s radial velocity resolution within an 11 x 11 deg region of the Galactic plane. The observations reveal that warm, ionized gas is widespread throughout the Galactic disk and that it has a complex morphology with faint, previously unidentified H-alpha emission regions superposed on a more diffuse H-alpha background. The H-alpha intensities indicate that, in the diffuse interstellar medium outside the discrete H II regions, the mean hydrogen ionization rate is about 3.5 x 10 to the 6th/s per sq cm column perpendicular to the Galactic disk and the mean square electron density of about 0.01 per cm to the 6th near the midplane. This warm, ionized gas appears to contain a substantial fraction (perhaps most) of the H(+) in the interstellar medium. The source of this ionization is not understood. Neither the faint emission regions nor the more diffuse emission appear to be associated with traditional H II regions immediately surrounding early-type stars. The high forbidden S II line 6716/H-alpha intensity ratios in the background clearly rule out scattered light as a primary source of the emission. Publication: The Astrophysical Journal Pub Date: December 1987 DOI: 10.1086/165811 Bibcode: 1987ApJ...323..118R Keywords: Background Radiation; H Alpha Line; Interstellar Matter; Milky Way Galaxy; Nebulae; Angular Resolution; Astronomical Maps; Early Stars; Gas Temperature; Ionized Gases; Radial Velocity; Astrophysics; GALAXIES: THE GALAXY; INTERSTELLAR: MATTER; NEBULAE: GENERAL; NEBULAE: H II REGIONS full text sources ADS | data products SIMBAD (4)