Density waves in the disks of two spiral galaxies.
Abstract
The disk galaxies NGC 495 (SBb) and NGC 1268 (SAb-c) both exhibit extremely smooth spiral arms. No obvious evidence of a young Population I component related to these arms is observed. The (U-R) colors in the arm and disk regions are identical to within 0.10 mag. This result, combined with the appearance of the arms, suggests that the spiral pattern in these galaxies represents the crests of a density wave in the stellar disk. The observed peak-to-peak amplitude of the density wave for both galaxies is approximately + or - 1/3 of the background disk light. This amplitude is comparable to the largest values observed by Schweizer (1976) for late-type spiral systems and is somewhat greater than current theoretical estimates of amplitudes derived from observational data by the use of linear density-wave theory.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1976
- DOI:
- 10.1086/182121
- Bibcode:
- 1976ApJ...206L..11S
- Keywords:
-
- Density Wave Model;
- Galactic Structure;
- Spiral Galaxies;
- Astronomical Photometry;
- Brightness;
- Color;
- Late Stars;
- Astronomy