The physical properties of S0 galaxy PGC 26218: the origin of starburst
  and star formation
  We present 2D-spectroscopic observations from Centro Astron\'omico Hispano
Alem\'an (CAHA) 3.5 m telescope and the millimetre observation from NOrthern
Extended Millimeter Array (NOEMA) of the nearby S0 galaxy PGC 26218, which
shows central star-formation activity and post-starburst outside in the disk.
We estimate the star formation rate (SFR = $0.28\pm0.01$ $M_{\odot} \rm
yr^{-1}$) and molecular gas mass ($\rm log\ $$M_{\rm H_{2}}=7.60\pm0.15\
M_{\odot}$) of PGC 26218 based on the extinction-corrected H$\alpha$ emission
line and the CO-$\rm H_{2}$ conversion factor ($\alpha_{\rm CO}$) 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 H$\alpha$, we find that the rotational axis of
CO($J$=1-0) is 45$^{\circ}$ different from that of H$\alpha$. In addition, the
profile of the CO($J$=1-0) emission line shows asymmetry and has an inflow
component of $\sim$ 46 $\rm km\ s^{-1}$. 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 $5.2\arcsec$ ($\sim$ 0.6 kpc) and the latter overlaps with one
of the optical cores. These results support that PGC 26218 may have experienced
a gas-rich minor merger, extending its star formation and locating it in the
SFMS.
