Observations of outflow and its consequences in circum-nuclear zones of spirals

Munoz-Tunon, C.; Beckman, John E.
Bibliographical reference

IN: Mass outflows from stars and galactic nuclei; Proceedings of the Second Torino Workshop, Turin, Italy, May 4-8, 1987 (A88-54076 24-90). Dordrecht, Kluwer Academic Publishers, 1988, p. 391-395.

Advertised on:
0
1988
Number of authors
2
IAC number of authors
2
Citations
0
Refereed citations
0
Description
The radial hydrogen (H2 + HI) distribution in spirals takes two forms: with a density peak at the nucleus or with a circular 'hole' around it. Spectral and photometric properties of selected spirals are examined, and cases of expansion in the circumnuclear gas, as well as ring structures in gas and stars are found. The correlation between absence of central gas and size of nuclear bulge (Sa galaxies have a lower bulge gas:stars ratio than Sc galaxies), plus the presence of LINERS in the interstellar medium close to the nucleus indicate probable outflow during starbursts. In NGC 6946, the outflow in H-alpha and N II was observed at velocities near 1000 km/s. In NGC 1068 and NGC 4736 expanding rings are found between 1 or 2 kpc, and in NGC 7331 a central LINER plus a static ring are observed at 4 kpc. Outflow from the nucleus is probably a common feature of the formation of central regions of spirals.