The shapes of spiral arms along the Hubble sequence.
Abstract
It is found, in light of shape and pitch angle measurements of the spiral arms in a large sample of nearby Sa-Sc galaxies, that neither logarithmic nor hyperbolic spirals accurately represent galactic arms. Within the limitations set by arm distortions, however, both forms may serve as interpolation functions in normal spirals. The measured pitch angles for 113 objects correlate weakly with arm structure and bulge-to-disk ratio, suggesting a less strict coupling of Hubble's classification criteria than has been previously believed. Maximum galaxy rotation velocity correlates with arm pitch, suggesting that the shape of the spiral pattern is dictated by kinematic parameters independently of the physical origin of the arms. A connection is also found between arm pitch and the absolute rotation velocity value rather than the angular velocity value.
- Publication:
-
The Astronomical Journal
- Pub Date:
- December 1981
- DOI:
- 10.1086/113064
- Bibcode:
- 1981AJ.....86.1847K
- Keywords:
-
- Astrometry;
- Galactic Rotation;
- Galactic Structure;
- Spiral Galaxies;
- Angular Velocity;
- Astronomical Models;
- Barred Galaxies;
- Kinematics;
- Pitch (Inclination);
- Spirals;
- Astronomy;
- Rotation:Spiral Galaxies;
- Spiral Galaxies:Morphology