2020ApJ...889..132G

We present 2D-spectroscopic observations from the Centro Astronomico Hispano Aleman 3.5 m telescope and millimeter observations from the NOrthern Extended Millimeter Array of the nearby S0 galaxy PGC 26218, which shows central star formation activity and post-starburst features in the disk. We estimate the star formation rate (SFR = 0.28 ± 0.01 M_☉ yr^–1) and molecular gas mass (logM_H2_=7.60±0.15 M_☉) of PGC 26218 based on the extinction-corrected Hα emission line and the CO-H₂ conversion factor (α_CO) of the Milky Way, respectively. We find that PGC 26218 follows the star-forming main sequence (SFMS) and the Kennicutt-Schmidt law. Comparing the kinematics of CO(J = 1-0), stars, and Hα, we find that the rotational axis of CO(J = 1-0) is 45° different from that of Hα. In addition, the profile of the CO(J = 1-0) emission line shows asymmetry and has an inflow component of ∼46 km s^–1. With the decomposition of the optical image, we confirm that PGC 26218 shows multiple nuclear structures. The projected offset between the most luminous optical center and the center of CO(J = 1-0) is 5.''2 (∼0.6 kpc) and the latter overlaps with one of the optical cores. These results indicate that PGC 26218 may have experienced a gas-rich minor merger, extending its star formation and locating it in the SFMS.