A comparison of spiral tracers in M81
- Ohio State Univ., Columbus (USA) Texas Univ., Austin (USA) National Radio Astronomy Observatory, Socorro, NM (USA) IBM Thomas J. Watson Research Center, Yorktown Heights, NY (USA) Vassar College, Poughkeepsie, NY (USA)
High-resolution digitized images of M81 in H I, B and I bands, H-alpha, and the radio continuum are studied. The H I gas, the nonthermal radio emission, the dust and the narrow dust filaments, the young stars, and the giant radio H II regions are each distributed across a broad spiral compression zone that starts near the measured position of the spiral velocity shock front and extends 1-2 kpc downstream from the shock front. Old and young stars both collect near the gravitational potential minimum on the arms. The evidence favors an SNR origin for the cosmic ray electrons that produce the nonthermal radio arms. The location of an H II region above or below the midplane explains the observed dispersion in the value of the visual extinction for the set of giant radio H II regions. Many of the general features of the spiral arms can be explained by density wave models that emphasize the cloudy nature of the interstellar medium. 57 refs.
- OSTI ID:
- 5019045
- Journal Information:
- Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 345; ISSN ASJOA; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CONFIGURATION
COSMIC ELECTRONS
COSMIC RADIATION
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
GALAXIES
H2 REGIONS
IMAGES
INTERSTELLAR SPACE
IONIZING RADIATIONS
LEPTONS
MAPS
ORIGIN
PHOTOMETRY
RADIATIONS
RADIOWAVE RADIATION
RESONANCE
SHOCK WAVES
SPACE
SPIRAL CONFIGURATION
STARS