We investigate the possibility that the Far-UV spectral energy distributions (SED's) of M31 and NGC 1399 differ only in the relative contribution from classical PAGB stars and in the amount of extinction. A good fit to the M31 spectrum is obtained for E(B-V) = 0.11 if about 65% of the flux comes from PAGB stars and the rest from stars of the type producing the far-UV emission in NGC1399. We speculate that the UV continuum in both galaxies is dominated by stars in post-horizontal branch phases of evolution, with a distribution of post-HB masses governed primarily by the metallicity and metallicity spread of the population. This hypothesis can qualitatively explain both the relative fluxes of UV rising branches in NGC1399 and M31 and the shapes of their SED's.

Line-of-sight velocity distributions are becoming increasingly important for our understanding of galactic structure. We present results obtained for the bulge of NGC7217 with a new deconvolution technique.

The results of the study of the global photometric parameters of ellipticals and bulges of spiral galaxies are presented.

We discuss the striking kinematic properties of the S0 galaxy NGC 4550. A detailed analysis of the line-of-sight velocity distribution (LOSVD) along the major axis shows that this galaxy contains two cold, cospatial, counterrotating disks with indistinguishable scale lengths and luminosities. The two disks, twins save the signs of their spin, are also found to have exponential luminosity profiles. We discuss qualitatively how this system might have formed.

The existing stellar kinematic evidence for massive black holes at the centers of galaxies is based on ≲ 30% discrepancies between constant M/L models and kinematic data. We show that asymmetries in the observed velocity distributions may introduce systematic errors in the data/model comparisons which are of the same order and have the same sign as these discrepancies. Existing modeling has so far failed to account properly for these asymmetries. Major axis data of M32 are analyzed as a specific example.

New insights in the structure of elliptical galaxies have been obtained indicating the presence of faint stellar disks in some of these systems. Clear correlations between the isophotal shapes, the kinematic, radio and X-ray properties of disky E's were found, suggesting that these galaxies form together with SO's a continuous transition of D/B ratio in the Hubble sequence (Bender et al. 1989). The isophotal shapes of these galaxies have been quantified by the fourth cosine coefficient a 4 of the Fourier expansion of the deviations from perfect ellipses, which yields positive values when the isophotes are pointed along the major axis (Carter 1987, Lauer 1985, Jedrzewski 1987, Bender and Möllenhoff 1987).

The metallicity difference of about an order between the kinematically decoupled nuclei and the surrounding bulges is found in 3 spiral galaxies possessing an axisymmetric potential in their centres.

The results of nuclear stellar population investigation are presented for 100 “normal” galaxies. The significant fraction of intermediate–age stars (T being about 1 billion years) is found in the nuclei of 50% of early–type disk galaxies.

On the diagram (Fe5270, Mg5175) ellipticals and bulges of disk galaxies (from S0 to Sc) maintain a very different position: E's seem to be overabundant in Mg, bulges seem to have a solar ratio Mg/Fe, except several ones who are overabundant in Fe.

The problem of determining the intrinsic shapes of elliptical galaxies cannot be solved using photometry alone. Measuring rotation on the apparent major and minor axes adds a kinematic constraint, but does not significantly improve the situation. We find that having two more spectra, at the ±45° position angles, gives enough kinematic information that much tighter limits can be placed on the intrinsic axis ratios than are possible otherwise.

The presence of triaxial bulges has been suggested as a mechanism for sweeping out the interstellar gas into the nuclear zones of normal spiral galaxies, giving rise to star formation processes (Zaritsky and Lo, 1986). In an initial phase of the present study, we have analysed the bulge component of a sample of spiral galaxies, obtained using the 4.2m WHT at La Palma Observatory, selected from among those which exhibit moderate activity. The results obtained are: (a) There is evidence, from the misalignment between the semi–major axes of the isophotes of the bulge and disc components, to support the presence of triaxial bulges in these galaxies; (b) The high spatial resolution of the images allows us to sample the bulges, showing that the surface brightness distribution is not always represented by a family of homologous coaxial ellipses, but rather by a set of ellipses which precess around a common centre, and whose ellipticity varies (see Beckman et al., 1991; Varela, 1992). It is possible to reproduce this structure with a family of concentric triaxial ellipsoidal shells. The presence of a disc offers the advantage of enabling us to interpret the geometry of the bulge correctly, but poses the disadvantage of requiring to interpret the disc emission in order to reconstruct that associated only with the bulge, i.e. to decontaminate the bulge from the disc light. To this end we carried out a photometric analysis, which enabled us to effect a valid bulge/disc decomposition. The preliminary results yielded by the analysis of the bulge component (after decontaminating the disc) show the presence of “transparent” discs in the galaxies analysed.

The observed spectrum of a galaxy is the composite spectrum of its stellar population broadened by the stellar velocities. Our topic is the extraction of the broadening functions (i.e., line-of-sight velocity distributions) from spectra. In the past, observers tried to extract only mean velocities and dispersions. But recent work on deconvolution [Franx & Illingworth ApJL327, L55 (1989), Bender A&A229, 441 (1990), Rix & White MNRAS254, 389 (1992), van der Marel & Franx ApJ, to appear] shows that more information can be recovered. The general idea is to compare a galaxy spectrum with one or more stellar ‘template’ spectra; but various methods differ widely in the treatment of noise and the control of sources of systematic error.

The CO(J=1→0) emission from NGC 4710, a star–forming S0 galaxy in the Virgo Cluster, was synthesized with spatial and velocity resolutions of 7″ and 26 km s—1, respectively. The CO shows a compact morphology and co–rotates with the galaxy's stars and nuclear optical emission line gas. Analysis of the CO distribution and kinematics indicates that the nuclear molecular gas is probably gravitationally unstable, and this may explain why the galaxy is presently forming stars. Four possible origins for the nuclear molecular gas are considered. An origin via bulge star ejecta being deposited into a residual interstellar medium is favored.

Imaging in the infrared (2.2μ) minimizes the impact of dust obscuration and allows reliable mapping of the mass-tracing stellar population in spiral galaxies. We find dramatic differences compared to photometry at shorter wavelengths (e.g. 0.8μ). As an example, the observations of the mini-bar and inner spiral arms of M 51 are discussed.

There is now mounting evidence that the intrinsic shape of elliptical galaxies and bulges of disk galaxies may generally be triaxial. There are different signatures of non–axisymmetric structures observed: velocity gradients along the minor axis (e.g. Davies & Birkinshaw 1986), twisting of the isophotes (e.g. Williams & Schwarzschild 1979) and misalignment between bulge and disk major axes (e.g. Bertola, Vietri & Zeilinger 1991). Therefore, a framework of reliable algorithms for the dynamical modelling of such triaxial potentials is needed.