Giant H II regions in M81

Abstract

view Abstract Citations (87) References (37) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Giant H II Regions in M81 Kaufman, Michele ; Bash, Frank N. ; Kennicutt, R. C., Jr. ; Hodge, P. W. Abstract H-alpha and VLA radio continuum observations at wavelengths of 6 and 20 cm are used to study the distribution of extinction and the distribution of giant radio H II regions along the spiral arms in M81. The radial distribution of visual extinction Av in the plane of M81 shows no trend, with an upper limit 0.1 mag/kpc for the radial extinction gradient and a mean Av of 1.1 + or - 0.4 mag. Nearly all the giant radio H II regions lie along the spiral arms or the inner H I ring. The radial distribution of the set of giant radio H II regions exhibits a strong maximum at a galactocentric distance R roughly 300 arcsec. Unless molecular hydrogen in M81 is also concentrated near R roughly 300 arcsec, the data disagree with Visser's (1980) model for star formation associated with a density wave. Some suggestions are made about how to change the ballistic particle model of Leisawitz and Bash to agree with the observed radial distribution of giant radio H II regions. Publication: The Astrophysical Journal Pub Date: August 1987 DOI: 10.1086/165433 Bibcode: 1987ApJ...319...61K Keywords: Astronomical Spectroscopy; H Alpha Line; Hydrogen Clouds; Radio Galaxies; Very Large Array (Vla); Nebulae; Radial Distribution; Radiant Flux Density; Astrophysics; GALAXIES: INDIVIDUAL MESSIER NUMBER: M81; NEBULAE: H II REGIONS; RADIO SOURCES: GALAXIES full text sources ADS | data products SIMBAD (1) NED (1)