Global spiral structure of M81 - radio continuum maps
VLA observations of the radio continuum emission from M81 at 6 and 20 cm are presented and used to check the predictions of density-wave theories. Both thermal and nonthermal radiation from the spiral arms are detected. Most of the bright knots along the radio arms are giant radio H II regions. The nonthermal emission defines spiral arms that are patchy and well-resolved, with a width of 1-2 kpc. The observed nonthermal arms are too broad to agree with the continuum gasdynamical calculations of Roberts (1969), Shu et al. (1972), and Visser (1978, 1980) for a classical density wave model. The observed arm widths appear consistent with the predictions of density-wave models that emphasize the clumpy nature of the ISM. The 20 cm arms appear to spiral outward from a faint inner H I ring, suggesting that the ring is produced by the inner Lindblad resonance. 36 references.
- Research Organization:
- Texas Univ., Austin; Ohio State Univ., Columbus
- OSTI ID:
- 6541534
- Journal Information:
- Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 310; ISSN ASJOA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CONFIGURATION
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
FLUX DENSITY
GALAXIES
H1 REGIONS
H2 REGIONS
INTERSTELLAR SPACE
MORPHOLOGY
POLARIZATION
RADIANT FLUX DENSITY
RADIATIONS
RADIOWAVE RADIATION
SPACE
SPIRAL CONFIGURATION