Morphological properties of galaxies in different Local Volume environments

We consider an all-sky sample of 1029 Local Volume (LV) galaxies situated within a distance of 11 Mpc. Majority of them have precise distances and estimates of hydrogen mass fraction and star-formation rate derived from far-ultraviolet or Ha fluxes. To describe an environment, we attribute two dimensionless values: the density contrast created by the most significant neighbour and the local density contrast produced by all neighbours within a separation of 1 Mpc. The hydrogen mass fraction exhibits a weak effect of HI deficiency being the most pronounced for irregular dwarf galaxies. The specific star formation rate (sSFR) is more sensitive to the environment than the hydrogen mass fraction. Almost all (99 per cent) LV galaxies have their sSFRs below -9.4 dex (yr(-1)). We notice that irregular dwarfs as well as late-type bulgeless galaxies are capable of reproducing their stellar mass with the observed sSFR over the cosmic time. Thus, the transformation of gas into stars in dIrs and spiral discs is rather sluggish unlike that in E, S0, dSph galaxies, whose star formation history has been stormy and short. The SFR(H alpha)-to-SFR(FUV) scatter ratio increases from Sc, Sd, Sm galaxies towards BCD, Im, Ir types which favours the idea of bursty star formations in lowmass galaxies. However, this bursty activity is caused rather by internal processes than by an external tidal action. A fraction of quenched E, S0, dSph galaxies increases from similar to 5 per cent in the field up to similar to 50 per cent in the densest regions.