Multiband Images of the Barred Galaxy NGC 1097
Abstract
We present B, V, R, J, H, and K broadband images of the barred galaxy NGC 1097. The optical and infrared colors maps trace the location of the major dust features. The dust lanes are relatively free of star formation and have low opacity. The depth of the dust lanes decreases as a function of wavelength so that they are deepest at B and shallower at H and K where they are difficult to detect. We find that the dust lane on the Northwest side of the galaxy has colors consistent with those of a dust screen with opacity derived from the galactic extinction law. Thus, it must be located on the near side of the galaxy. The colors in the dust lane on the Southeast side of the galaxy, on the other hand, suggest that there are stars both in front of and behind the dust, consistent with this dust lane being located on the far side of the galaxy. From the K images, we estimate that the total stellar mass of the star forming spiral ring at a radius of - 1 kpc from the nucleus is of the same order as the molecular gas mass in the ring. The infrared images show a short bar inside the inner spiral ring. In the principal plane of the galaxy, the short bar is not perpendicular to the prominent outer bar. This suggests that there are torques between the inner bar and the spiral ring and that this inner bar may have a pattern speed different from the outer bar. Near the inner spiral ring (at ~17" = 1.4 kpc from the nucleus), the dust lane becomes double peaked with a peak to valley extinction ratio similar to that observed in radio continuum by Ondrechen & van der Hulst (1983). This suggests that if the cold diffuse component of the interstellar medium (traced by the dust) moves with the cosmic ray electron component then the magnetic field pressure is not a significant force in the shocks. Alternatively if the two phases do not move together a more detailed comparison may show differences in the shock shapes.
- Publication:
-
The Astronomical Journal
- Pub Date:
- July 1995
- DOI:
- 10.1086/117503
- arXiv:
- arXiv:astro-ph/9503067
- Bibcode:
- 1995AJ....110..156Q
- Keywords:
-
- GALAXIES: INDIVIDUAL: NGC 1079;
- GALAXIES: ISM;
- GALAXIES: STELLAR CONTENT;
- Astrophysics
- E-Print:
- uuencoded compressed postscript of paper. Tarred compressed paper and figures are available by anonymous ftp at ftp://payne.mps.ohio-state.edu/pub/quillen/n1097/