Isolated lenticular galaxies: properties and evolution
  This work is dedicated to investigation of galaxies that do not fit into a
common scenario of galaxy formation - isolated lenticular galaxies. We have
studied stellar populations and ionized gas content of a sample of 22
lenticular galaxies (among those 4 targets have appeared to be of erroneous
morphological classification) by undertaking deep long-slit spectroscopy with
the Russian 6-m telescope and with the Southern African Large Telescope (SALT).
The obtained average ages of the stellar populations in bulges and discs covers
a wide range between 1.5 and >15 Gyr, that indicates the absence of distinct
epoch of their stellar content formation. In contrast to galaxies in groups and
clusters, the stellar population ages in bulges and discs of isolated
lenticulars tend to be equal, that supports the inefficiency of the bulge
rejuvenation in sparse environment. Almost all the lenses and rings possess
intermediate ages of the stellar populations, within the range of 2-5 Gyr. By
analyzing the emission-line spectra of galaxies, we have found that 13 out of
18 (72+/-11 %) objects of our sample possess extended emission-line structures;
among those, 6 galaxies (46+/-14 %) demonstrate decoupled gas kinematics with
respect to their stellar discs. We have found starforming off-nuclear regions
in 10 galaxies; their gas oxygen abundances are nearly solar that implies tidal
gas accretion from gas-rich dwarf satellites rather than accretion from
cosmological large-scale structure filaments.
