Binary galaxy statistics. III. Correlations in angular measures, sense of rotation, and type.
Abstract
A sample of 94 pairs of galaxies with known radial velocities, major and minor axes, types, and relative position angles of the major axis, shows some indications of common orbital motion for the spirals. In particular, although the inclinations are uncorrelated, there is a weak tendency of the sense of spiraling to match, for the two images to lie parallel to each other, and for the most elongated images to point at each other. Spirals clearly tend to pair with spirals and ellipticals with ellipticals (S0's were put with spirals). Furthermore, the rms velocity dispersion for spiral-spiral pairs is 220 km/s and for pure elliptical pairs it is 330 km/s, but for mixed spiral-elliptical pairs it is 540 km/s. This strongly suggests that the mixed pairs are contaminated with optical pairs and that very few galaxies have been misclassified. It is suggested that many or most of the pairs were once in triple or larger systems and that part of the original correlation in orbital properites was lost in the process of tidal stripping or ejection of the pair or the outliers.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1979
- DOI:
- 10.1086/157023
- Bibcode:
- 1979ApJ...229..877N
- Keywords:
-
- Elliptical Galaxies;
- Galactic Clusters;
- Galactic Structure;
- Spiral Galaxies;
- Statistical Distributions;
- Angular Momentum;
- Frequency Distribution;
- Radial Velocity;
- Astrophysics;
- Pairs of Galaxies:Statistics;
- Pairs of Galaxies:Structure;
- Pairs of Galaxies:Velocity Dispersions