View of the galactic H-alpha background - l = 208-218 deg, b = -2 to +8 deg

Journal Article · Tue Dec 01 04:00:00 EST 1987 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/165811· OSTI ID:5345673

Reynolds, R J

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. 31 references.

• Research Organization: Wisconsin Univ., Madison
• OSTI ID: 5345673
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 323; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BACKGROUND RADIATION
BALMER LINES
COSMIC RADIO SOURCES
ELECTRON DENSITY
FLUIDS
GALAXIES
GASES
H2 REGIONS
INTERSTELLAR SPACE
IONIZATION
IONIZED GASES
MILKY WAY
MORPHOLOGY
NEBULAE
RADIAL VELOCITY
RADIATIONS
SPACE
VELOCITY