| Abstract: | The sample of galaxies within 7 Mpc has been compared with that of the Virgo cluster in order to find new and confirm already known differences which may be caused by the environment. The well-known morphology-density relation is found to be valid not only for luminous galaxies but also for faint objects. The differences in the global luminosity functions are mainly caused by the different composition of the samples, whereas the luminosity functions of narrow morphological subgroups, with the exception of the irregulars, probably are not dependent on the density or on other quantities. The already observed HI-deficiency of the interstellar medium of the Virgo cluster spirals has been confirmed. There is a steep drop of this quantity with increasing distance from the dominant galaxies M 87 and M 49. The interstellar dust masses of Virgo cluster spirals and irregulars have been estimated from far-infrared fluxes. These data have been combined with the HI masses in order to obtain the gas-to-dust ratios, which come out to be smaller by a factor of 4 for the Virgo cluster spiral galaxies than for the nearby systems, on the average. The gas-to-dust ratio is strongly correlated with the HI-deficiency. These results support the concept of the ram pressure of the intracluster medium on the spiral galaxies in the core of the Virgo cluster. |
