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NGC 7714 galaxy emission line spectrum indicating strong excitation and velocity gradients in excited gas due to rotation

The distribution of ionized gas as deduced from the emission lines seen using the nebular spectrograph is described for more than 30 spiral and irregular galaxies. From the comparison of estimates of the relative intensities of H alpha and STAN/sub II! lambda 6583, with relative intensities computed by the usual techniques, it is concluded that the major regions of emission in the outer- parts of galaxies and in the spiral arms, where the H alpha /STANII! lambda 6583 ratio is --3, are similar to the extended H /sub II/ is regions in this galaxy. The investigation has substantiated the result that irregular galaxies have the highest propontion of ionized gas and that this decreases steadily through barred spirals of types SBc and SBb and normal spirals of types Sc, Sbc, Sb, and Sa. Throughout irregular galaxies and in the nuclear, as well as the spiral-arm, regions of SBc and SBb galaxies and some Sbc and Sc galaxies, there must be a considerable population of massive luminous stars. The nuclei of other Sc and Sbc galaxies and the nuclei in the majority of Sb galaxies contain less ionized gas than do the spiral-arm regions. The most striking observational result is thatmore » between the outer parts and the nuclear regions in many of the latter galaxies, the ratio of the strengths of H alpha and STAN/sub II/! lambda 6583 decreases from about 3 to --1 to 0.1. This reversal is most common in Sb and Sa galaxies having large prominent nuclei and well-developed nuclear bulges, but it appears in Sc galsxies having small nuclei. This can be explained either by a general deficiency of hydrogen in these regions or by supposing that radiative processes are comparatively unimportant in those nuclei where the light comes mainly from K giants, and that collisional ionization and excitation take place in the gas at an electron temperature of 20000 to 40000 deg , or having energies of a few electron volts, since such excitation may be non-thermal. These excitation conditions might arise through corpuscular radiation from stars. Whether such an explanation for the anomalous ratios is accepted depends on estimates of the energy supply required to maintain such a high electron temperature against cooling mainly by line emission. This requires absolute measurement of emission-line intensities. (auth)« less

The properties of galactic halos of radio emission and models that were proposed to account for the condition of our own galactic halo are briefly reviewed. A new model is then proposed in which it is argued that the halos about normal galaxies such as our own and M31 may be transient phenomena that were produced as the result of a violent outburst in the nuclear region of a galaxy. The time scale to be associated with such a halo lies in the range 5 x 10/sup 7/10/sup 9/ years, depending on the conditions that are developed in the gas following the outburst. On this picture the explosion of the center was also responsible for the outwardmoving gas that is seen in the disk of our galaxy, and it appears from this that the outburst took place about 10/sup 7/ years ago. The high-energy particles that fill such a halo may have come from the intergalactic medium, or they too may have been produced in the outburst. Violent events of this type may be recurrent in some galaxies. (auth)

Black hole objects in elliptical galaxies, using stellar light and velocity dispersion distribution in nuclear regions for mass limits

In these lectures I shall largely be concerned with the view that the bulk of the primary cosmic rays is of extragalactic origin. In order to set the stage for these ideas, a survey of the components of the extragalactic universe will be given. Then much of the discussion will centre about the various types of extragalactic non-thermal sources.

A photographic 200-inch plate of the compact cluster of galaxies Shakhbazian I is presented and discussed. The size of the cluster, the nature of the galaxies and the very small velocity dispersion all make this cluster unique. The mass-to-light ratio of the cluster is 0.3-0.5.

The gravitational red-shift of the spectral lines is considered as the only possible means to detect stars containing neutron cores, assuming that there are sufficient energy sources available to make the star bright enough to be detected at all. A star in this highly evolved state would contain energy enough to be detectable only for a limited time. (C.E.S.)

Catastrophic implosion analysis in stars with masses greater than critical mass in which general relativity becomes dominant

Absorption and emission redshift distribution in quasars, N systems and similar compact and radio galaxies

Physical properties of peculiar A and B stars, especially their anomalous abundances and positions in H-R diagram