Nobeyama Radio Observatory report, no. 378: The polar ring spiral galaxy NGC 660
Abstract
NGC 660 is a unique, nearby, peculiar polar ring spiral LINER galaxy with two distinct morphological and kinematic components: a spiral disk, seen almost edge-on (i approximately 70 deg), with a major axis position angle of 45 deg and a diameter of approximately 11 kpc (D=13 Mpc, Ho = 75 kms-1 Mpc-1), and an outer polar ring (p.a. 170 deg) with a diameter of 31 kpc, inclined on average 55 deg with respect to the disk major axis. It was mapped in the 21 cm HI line with a resolution of 13 inches x 60 inches and in the CO(1-0) and CO(2-1) lines with a 12 inches -22 inches beam. B, V, R, I, J, H, K prime-band images, and a long-slit H(alpah) spectrum along the disk major axis were obtained as well. It has been morphologically classified as SBa, but our data show it has the global characteristics of a later-type (Sc?), gas-rich disk. The disk and the polar ring both have an exponential luminosity profile, with scalelengths of 1 3 and 3.9 kpc, respectively. The polar ring is blue (V-I approximately 1.0), indicating a stellar population age of a few billion years, according to our stellar population synthesis model and the nucleus is red (V-I approximately 1.8). H(alpha) images show HII regions throughout the polar ring. The near-infrared images show a boxy/X-shape of the bulge and 1.4 kpc long linear features along the disk major axis on both sides of the bulge. The disk was detected in radio continuum at 21 cm. It has a compact 300 mJy nuclear source and an extended (7.5 kpc diameter) component of 80 mJy. The central source has a very high radio power for a spiral galaxy, while the disk has a normal radio power. The radio spectral index is -0.57, indicating an important contribution from thermal radiation.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- 1995
- Bibcode:
- 1995STIN...9529097V
- Keywords:
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- Astronomical Observatories;
- Infrared Imagery;
- Kinematics;
- Luminosity;
- Morphology;
- Photometry;
- Ring Galaxies;
- Spiral Galaxies;
- Stars;
- Line Spectra;
- Microwave Spectra;
- Optical Properties;
- Radiant Flux Density;
- Stellar Models;
- Thermal Radiation;
- Astrophysics