Results are presented of optical imaging of the low redshift BAL QSO 1411+442, in four colours. The host galaxy is revealed as an inclined spiral galaxy with a long arm which may be a tidal tail. There also appears to be connecting luminosity to two nearby objects. There is a straight blue feature emerging from the nucleus and Ha emission from an oppositely directed filament. [O III] appears to be enhanced in some outer regions. While the host galaxy is more exotic than usual for QSOs, it is not obvious how these properties are connected with the BAL phenomenon.

Deep optical imaging of Mkn 231 reveals twin (tidal?) tails, a linear nuclear feature at green wavelengths, and a very blue region 4 arcsec south of the nucleus. Much of the central part of the galaxy is red, but there are complex areas of blue luminosity outside this, and a sharp edge to the luminosity at a distance of ~16 arcsec from the centre. Overall, the host galaxy appears to have a normal optical luminosity and blue colour (B-R ~0.7) despite being one of the most luminous galaxies known in the infrared. Radio emission in the system is extended on one side on a similar scale to the optical tails, but shows no detailed correspondence with optical structure; in particular there is no radio counterpart to the optical ‘jet’. Examination of IUE archival data indicate that the UV flux is very weak and the UV spectrum is peculiar for a Seyfert galaxy. The UV observations provide evidence for considerable nuclear extinction in the system, in accordance with previously published optical and infrared work, but the UV extinction is unlike Galactic absorption and may be more similar to that seen in the LMC. Recent optical spectra of Mkn 231 show changes in both the emission line spectrum and in the strong broad absorption lines (BAL), compared with previously published observations. This places strong limitations on the size of the nuclear continuum source. We suggest that Mkn 221 is a recently merged system which is currently undergoing star-formation, and discuss the connection with BAL QSOs.

At least two southern Seyfert 2 galaxies show a double peak in their [OIII] line profiles. Spatial spectroscopy shows each peak to associate with a separate Seyfert 2 nucleus. Separations are of the order of 1 arcsec (1 kpc). The implications and the status of these objects are discusssed.

The influence of the environment on the origin of radio radiation from galaxies is studied by compairing the occurence of radio emission in galaxies in compact high density groups of Hickson (1982) with that in field galaxies of similar types. The study shows that the fractional luminosity functions of elliptical and spiral galaxies in compact groups are similar in shape to that of field galaxies but the probability of a compact group galaxy being a radio source is 5 to 10 times greater than that of an isolated galaxy of the same type. Radio Loud group ellipticals tend to be the optically brightest galaxy in the group independent of their absolute luminosity.

It is shown that the power of radio emission of spiral members of double galaxies depends on their projected distances. For example, the members of pairs with projected distances lower than 10 kpc are 2–2.5 times more powerful than members of pairs with distances larger than 50 kpc. Since 90% of “interacting” spiral galaxies belong to pairs with separations smaller than 50 kpc this means that the members of interacting pairs are more powerful radio emitters than the components of non-interacting pairs.

LINER's (Low-Ionization Nuclear Emission-line Regions) are found in the majority of early-type (Sb or earlier) galaxies, and in some late-type and peculiar galaxies as well. Because they are so common but are not energized by normal stars, their nature is critical to our understanding of both the active galactic nucleus phenomenon and the evolution of normal galactic nuclei. After briefly reviewing the spectroscopic basis of the LINER classification, I summarize four alternative models for LINER's: 1) LINER's as “mini-Seyferts” in which the emission-line gas is photoionized by a more dilute version of the high-energy nonstellar continuum found in Seyfert nuclei. 2) LINER's as accretion flows of cooling gas originating in the halos of galaxies and/or in the intra-cluster medium. 3) LINER's as starburst-driven winds. 4) LINER's as colliding, shock-heated galaxies. After reviewing the evidence, I conclude that it is very likely that several (and possibly all) of the above models are needed to account for the diverse properties of LINER's. While LINER's would then not have a single unified explanation, they would have a direct bearing on many issues in extragalactic astronomy.

The results of a sensitive radio and optical survey of nearby early-type galaxies show that most (perhaps all) bright ellipticals have ‘active’ nuclei. These are characterized by a central non-thermal radio source and a weak LINER-like optical emission spectrum. There appears to be a smooth continuity in optical and radio properties from the weakest nearby sources to strong radio galaxies. Galaxies with radio sources usually show optical emission lines, but there is no simple relationship between gas content and radio power.

A sensitive search for intrinsically faint Seyfert nuclei in the 500 brightest northern galaxies is being conducted with the Hale 5.08 m telescope. The primary aim is to extend the luminosity function of active galactic nuclei (AGNs) to lower luminosities. Thus far, we have detected Hα emission having full-width near zero-intensity (FWZI) ≳ 4000 km s−1 in a significant fraction (≳10%) of nearby galaxies. Moreover, the narrow emission lines in a given nucleus often have markedly different widths, as shown in detail for M81. Those associated with high critical densities are generally the broadest, indicating that a very wide range of densities is present in the narrow-line region. The relative intensities of the lines can readily be explained with models in which clouds of gas having ne ≈ 102 to 107 cm−3 are photoionized by nonstellar radiation such as that produced by QSOs and luminous Seyfert 1 galaxies.

Modern detectors permit astronomers to examine galaxies at very low light levels, at very high velocity resolution, and for nearby objects, at very high spatial resolution. Such observations will lead to phenomenon not previously detected, and offer new insights into the phenomena we presently lump under the heading of “activity.”

The very large majority of the galaxies selected in X-ray surveys are active galaxies (e.g. narrow emission line galaxies, Seyfert galaxies etc.). There are however a few examples of normal galaxies, which are sometimes characterized by an X-ray luminosity in excess of what is expected on the basis of their optical appearance. A closer look at these galaxies may reveal the presence of a mini active nucleus or of other processes responsible for the powerful X-ray emission. Here we consider the normal galaxies selected in the Medium Sensitivity Survey and we discuss the properties of the most X-ray luminous one. We show that this object, which has an optical spectrum lacking any evidence of nuclear activity and which has a radio luminosity typical of early type galaxies, is indeed a peculiar galaxy surrounded by a hot (>2 keV) halo extending out to a radius of 300 kpc, implying a total mass of ∼3 × 1013 M⊙.

It is argued that the tightly wound spiral structure in the nuclei of some galaxies -generally referred to as rings- provides evidence of nuclear activity. It is shown that such spirals are the loci of plasma ejected in a bi-polar fashion from the equator of a rotating nucleus and funneled by a magnetic field. The equation of the loci is derived and applied to the nuclear spiral of NGC 4736. The observed rotational and angle-dependent ejection velocities, as well as polarization of non-thermal continua give support to our model.

Radio and optical evidence for activity in the spiral galaxy NGC4319 is presented. N4319 appears to be one of the first spirals to exhibit double lobe radio structure outside of the nuclear regions. The optical data show that 1) the quasar M205 is connected to the nucleus of N4319 and 2) that a similarly connected region on the opposite side of the nucleus is expanding towards us with V ~ 103 km s−1. It is suggested that the unusual Hα/[NII] λ 6583 ratio (≤ 0.3) indicates that the entire central (7 kpc diameter) disk of N4319 has been shock excited by this activity.

It is found that the relation between the presence of radio emission and the degree of central concentration (i.e. the Byurakan class) of spiral galaxies is valid only for barred spirals. Barred spirals are also found to have central radio sources more often than normal spirals which are generally disc radio emitters.

As a step towards the understanding of the phenomena occurring in galactic nuclei, we find that the ratio between the radio continuum emission of the nuclei of spiral galaxies and their optical luminosity is related to optical signs of nuclear activity, such as the emission line strengths of the H∝ and [NII] λ6584 lines.

A significant fraction of all spiral galaxies exhibit some type of “activity” in their nuclear regions as evidenced by the presence of emission lines in their optical spectrum (Keel, 1982; Cetty-Veron and Veron, 1985). It has become standard to classify emission-line galaxies into two main groups: “active” having Seyfert or Liner nuclei and “inactive”, having Starburst or HII-region like nuclei. Two main classification criteria are used, one based in the widths (Khachikian and Weedman 1974) the other in the intensity ratios of the nuclear emission lines (Baldwin, Phillips and Terlevich, 1981).

VLBI observations show that the center of the nearby (~ 3.3 Mpc distant) spiral galaxy, M81, consists of a single elongated radio core, of dimensions 1000 × 4000 AU, with the major axis aligned, in projection, within 3° (<1σ) of the galaxy's rotation axis. This morphology can be interpreted in terms of an active galactic nucleus (AGN) with either a core-jet structure residing in M81's center or an accretion disk filling out the broadline region of this center. In contrast, the radio structure in the companion galaxy, M82, is very complex. VLBI observations of M82 yield the diameters and spectral index distribution of the hot spots, and the morphology and expansion velocity of the brightest hot spot, 41.9+58. Our results argue against the hot spots being core and jet condensations, or young supernovae (SNe), or typical supernova remnants (SNRs). We suggest that the hot spots in M82 are the remnants of stellar events that yielded some combination of SNRs and “exotic” objects.

A dust ring surrounds the central starburst region in M 82, resulting in strong additional reddening of light emerging near the equator. The starburst is contained in a flattened, optically thick region inside this ring. The concentration of scattered light near the minor axis is explained as the combined action of the cos ϑ-emission-law of the flat source and the shadowing by the ring. The dust ring may be spatially coincident with the CO-ring.

The star formation in galactic open clusters leads, as a rule, to a complete disruption of the latter (Tutukov, 1978) because of the shallow potential wall of these clusters. The matter of dense galactic nuclei is in deep potential walls what drastically changes the star formation regime. The numerical dynamical model of the star formation in galactic nuclei with the mass 6 109 M⊙ and the radius ~ 430pc was proposed by Loose et al (1982). It includes old and newly-formed stars, gas and dust distributed initially as in the center of our Galaxy. The model takes into account the star formation, supernova explosions, stellar winds, the turbulent motion of the gas component, non-grey radiative energy transfer, the influx of gas from old stars and from the outside. The main parameter of our model is the time of dissipation of the kinetic energy of the gas component Td . Supernova explosions are the main source of this energy. The results of numerical experiments help to point out two main regimes of the star formation in galactic nuclei: stationary and bursting. In the stationary regime the rate of the star formation is constant and it equals to the rate of the gas input. The formation of a long-living superstar is possible in this case (Krügel, Tutukov, 198b). In the bursting regime the periods of an active star formation alternate with those of almost a complete absence of the star formation. The main reason for supressing the star formation process is supernova explosions which throw the gas out of the galactic nuclei.

We have been observing a range of galaxy type over the IR through millimetre region to determine the contribution of thermal emission from heated dust. It is now clear that the ‘Starburst’ phenomenon is widespread and has a range of luminosity. By studying the continuum spectrum of the radio-loud Seyfert galaxy NGC1275 over many years, we have shown that it possesses a thermal component of luminosity comparable to the synchrotron luminosity. We interpret this thermal component as emission from dust heated by stars forming from material in an X-ray cooling accretion flow.

The results of spectrophotometry of two nuclei of NGC 6240 are presented. One of them has properties of Sy 2 nucleus, the other seems to be a complex of HII regions.