Research of signs of star formation in three S0 galaxies - members of isolated pairs

Abstract

We obtained and analyzed long-slit spectra of three lenticular galaxies with optical rings: PGC 48114, ESO 234-011, and ESO 444-076. Ionized gas was detected in all of them. In PGC 48114, the excitation mechanism of the ionized gas differs along the ring, despite the consistent kinematics of the ionized gas and stars, as we showed earlier. Narrow-band images of PGC 48114 in the H$α$ and [NII]$λ$6583 emission lines revealed a star formation arc in the northwestern part of the ring. In ESO 234-011 and ESO 444-076, the ionized gas along the long slit is shock-excited and have kinematic discrepancy with the stars. This implies accretion of matter at an angle to the main disk of the S0 galaxies, which likely inhibits ongoing star formation. The companions of these S0 galaxies are late-type galaxies with extensive ongoing star formation. These companions may be the sources of the gas, or each pair may be feeding from a common gas reservoir.