We present the environmental dependence of the luminosity-size relation of galaxies in the local universe (z < 0.01) along with their dependence on galaxy morphology represented by five broad types (E, dEs, S0, Sp, and Irr). The environmental parameters we consider are the local background density and the group/cluster membership together with the clustercenteric distance for the Virgo cluster galaxies. We derive the regression coefficient (β ), i.e., the slope of the line representing the least-squares fitting to the data and the Pearson correlation coefficient (c.c.) representing the goodness of the least-squares fit along with the confidence interval from bootstrap resampling. We find no significant dependence of the luminosity-size relation on galaxy morphology. However, there is a weak dependence of the luminositysize relations on the environment of galaxies, in the sense that galaxies in the low density environment have shallower slopes than galaxies in the high density regions except for elliptical galaxies that show an opposite trend.

The environmental dependence of the morphology of dwarf galaxies in isolated satellite sys- tems is analyzed to understand the origin of the dwarf galaxy morphology using the visually classified morphological types of 5836 local galaxies with z . 0.01. We consider six sub-types of dwarf galaxies, dS0, dE, dEbc, dSph, dEblue, and dI, of which the first four sub-types are considered as early-type and the last two as late-type. The environmental parameters we consider are the projected distance from the host galaxy (rp), local and global background densities, and the host morphology. The spatial distributions of dwarf satellites of early-type galaxies are much different from those of dwarf satellites of late-type galaxies, suggesting the host morphology combined with rp plays a decisive role on the morphology of the dwarf satellite galaxies. The local and global background densities play no significant role on the morphology of dwarfs in the satellite systems hosted by early-type galaxies. However, in the satellite system hosted by late-type galaxies, the global background densities of dE and dSph satellites are significantly different from those of dEbc, dEblue, and dI satellites. The blue-cored dwarf satellites (dEbc) of early-type galaxies are likely to be located at rp > 0.3 Mpc to keep their cold gas from the ram pressure stripping by the hot corona of early-type galaxies. The spatial distribution of dEbc satellites of early-type galaxies and their global background densities suggest that their cold gas is intergalactic material accreted before they fall into the satellite systems.

We analyze the dependence of disk morphology (arm class, Hubble type, bar type) of nearby spiral galaxies on the galaxy environment by using local background density (n), projected distance (rp), and tidal index (T I) as measures of the environment. There is a strong dependence of arm class and Hubble type on the galaxy environment, while the bar type exhibits a weak dependence with a high frequency of SB galaxies in high density regions. Grand design fractions and early-type fractions increase with increasing n, 1/rp, and T I, while fractions of flocculent spirals and late-type spirals decrease. Multiple-arm and intermediate-type spirals exhibit nearly constant fractions with weak trends similar to grand design and early-type spirals. While bar types show only a marginal dependence on n, they show a fairly clear dependence on rp with a high frequency of SB galaxies at small rp. The arm class also exhibits a stronger correlation with rp than n and T I, whereas the Hubble type exhibits similar correlations with n and rp. This suggests that the arm class is mostly affected by the nearest neighbor while the Hubble type is affected by the local densities contributed by neighboring galaxies as well as the nearest neighbor.

High resolution images of the nuclear regions of nearby galaxies show that nuclear spirals are preponderant in normal galaxies as well as in active galaxies. These nuclear spirals, especially the grand-design nuclear spirals are found to be formed by the gas flow driven by the bar. Hydrodynamical simulations exploring a wide range of parameter space show that the morphology of nuclear spirals depends not only on the inner dynamics but on the global dynamics resulting from the global mass distribution of galaxies. Thus, the nuclear morphology can be a diagnostic tool for the inner dynamics of galaxies when the global mass distribution is taken into account.

Owing to several observational evidences and theoretical predictions for morphological evolution of galaxies, it is now widely accepted that galaxies do evolve from late types to early ones along the Hubble sequence. It is also well established that non-axisymmetric potentials of bar-like or oval mass distributions can change the morphology of galaxies significantly during the Hubble time. Here, we review the observational and theoretical grounds of the secular evolution driven by bar-like potentials, and present the results of SPH simulations for the response of the gaseous disks to the imposed potentials to explore the secular evolution in the central regions of barred galaxies.

We have conducted a V, I, J, and H surface photometry of a barred galaxy NGC 4314 to analyze the morphology and luminosity distribution of the galaxy. By applying a semi two-dimensional profile decomposition method, we derived the luminosity fractions and the scale lengths of the three distinct components, bulge, disk, and bar: Lb ≈ 0.35, Ld ≈ 0.35, Lbar ≈ 0.30, re ≈ 22", ro ≈ 50", and a ≈ 60". The bulge of NGC 4314 seems to be triaxial due to the isophotal twists but its luminosity distribution is well approximated by the r1/4-law.

We analyzed the luminosity profiles of 104 bright barred galaxies to examine the frequency of occurrence of the Type II disk which is thought to be the result of redistribution of disk material by bar potential. Our analysis of the elliptically averaged major axis profiles shows that about 70% of the present sample seem to have Type II disks with a weak tendency of preferential occurrence of type II disks in the late type galaxies. there is a subgroup of Type II disks which is characterized by a flat luminosity distribution in the middle disk, followed by a steep decline in the outer parts. Most of the galaxies with strong bars tend to have Type II disks. The present study strongly suggests that Type II disk is an evidence for the secular evolutions in disk galaxies.

The global morphology and geometric parameters of 39 barred galaxies are investigated, by using isophote map and isodensity tracings obtained from detailed surface photometry with the Kiso V-band plates. The observed results are as follows: i) There is no strong indication that the ratio of bar length to disk size is correlated with Hubble type, except that the largest bars appear in the SBb galaxies. ii) The mean value of axial ratios of bars is 2.0 ± 0.4 and there is a trend that early type galaxies have smaller axial ratios than late type galaxies. iii) About 15% of early type barred galaxies(Sb0-SBb) have triaxial bulges.