Kinematics and excitation of ionized gas in the stellar counterrotating galaxies PGC 35706 and LEDA 2220522

Abstract We compare the kinematics and excitation of ionized gas in the stellar counterrotating galaxies PGC 35706 and LEDA 2220522. We assess the regularity of gas rotation using an axisymmetric model, two spectral analyses of the same observations, and emission-line diagnostics. The stellar and gas velocity gradients are nearly opposite in both galaxies, but the gas properties differ. In LEDA 2220522, the root-mean-square residual of the gas model is 5.90 km/s. The two analyses agree in both the gradient direction and local velocities, supporting regular gas counterrotation. In PGC 35706, structured residuals have a root-mean-square value of 45.5 km/s, dominated by a few bins with extreme velocities. Agreement between the two analyses is substantially poorer at the level of local velocities. Excitation diagnostics identify regions consistent with star formation in LEDA 2220522. In PGC 35706, weak, low-ionization emission provides no basis for estimating the star formation rate from Hα. Interpreting gas counterrotation therefore requires separate assessments of the velocity-gradient direction, the regularity of the velocity field, and gas excitation.