Extended Gaseous Disk in the S0 Galaxy NGC 4143

We present the results of our spectroscopic study of the lenticular galaxy NGC 4143—a peripheral member of the Ursa Major cluster. Using the observations at the 6-m SAO RAS telescope with the SCORPIO-2 instrument and the archival data of panoramic spectroscopy with the SAURON instrument at the WHT, we have detected an extended inclined gaseous disk in this lenticular galaxy with a spin approximately opposite in direction to the spin of the stellar disk up to a distance of about 3.5 kpc from the center. The galaxy images in the H $$\alpha$$ and [N II] $$\lambda$$ 6583 emission lines obtained at the 2.5-m CMO SAI MSU telescope with the MaNGaL instrument have shown that the emission lines are excited by a shock wave. A spiral structure absent in the stellar disk of the galaxy is clearly seen in the brightness distribution of ionized-gas lines (H $$\alpha$$ and [N II] from the MaNGaL data and [O III] from the SAURON data). A complex analysis of both the distribution of Lick indices along the radius and the integrated colors, including the ultraviolet measurements with the GALEX space telescope and the near-infrared measurements with the WISE space telescope, has shown that there has been no star formation in the galaxy, possibly, for the last 10 Gyr. Thus, the recent external-gas accretion event in NGC 4143 was not accompanied by star formation, probably, due to an inclined direction of the gas inflow onto the disk.