Mathematics – Logic
Scientific paper
Mar 1995
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995aj....109..942v&link_type=abstract
Astronomical Journal (ISSN 0004-6256), vol. 109, no. 3, p. 942-959
Mathematics
Logic
47
Dynamic Characteristics, Galactic Mass, Galactic Structure, Infrared Spectra, Peculiar Galaxies, Radio Observation, Spiral Galaxies, Visible Spectrum, Carbon Monoxide, Data Correlation, H Lines, Image Analysis, Rotation, Spectrum Analysis, Star Formation, Velocity Distribution
Scientific paper
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 45deg and a diameter of approximately 11 kpc (D = 13 x 60 arcsec and in the CO(1-0) and CO(2-1) lines with a 12-22 arcsec beam. B,V,I,J,H,K'-band images, and a long-slit H-alpha 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 scale lengths 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 H II 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. The H I line observations show absorption against the nuclear source, and both H I and CO line data show emission from the disk and the polar ring. The H I and CO data indicate a rather flat disk rotation curve, with a rotation velocity of approximately 150 km/s. From our H-alpha spectrum, taken close to the major axis, a steeper inner gradient and a consideraably lower rotation velocity (approximately 110 kms/s) is derived in the outer parts than from that of Benvenuti et al. (l976), if one assumes the disk to be flat and in circular rotation.
Arimoto Nobou
Casoli Fabienne
Combes François
Driel Wim van
Geng F.
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