Extended Gaseous Disk in the S0 galaxy NGC 4143

TL;DR

This study reveals an extended, inclined gaseous disk in the S0 galaxy NGC 4143, showing signs of external gas accretion without recent star formation, and highlights complex gas dynamics and shock excitation in the galaxy.

Contribution

First detailed spectroscopic analysis of NGC 4143 revealing an extended inclined gaseous disk with shock-excited emission lines and no recent star formation.

Findings

Detected gaseous disk extending up to 3.5 kpc with opposite spin to stellar disk

Emission lines excited by shock waves, indicating external gas accretion

No evidence of star formation in the last 10 Gyr

Abstract

We present our results of the spectroscopic study of the lenticular galaxy NGC 4143 - an outskirt member of the Ursa Major cluster. Using the observations at the 6-m SAO RAS telescope with the SCORPIO-2 spectrograph and also the archive data of panoramic spectroscopy with the SAURON IFU at the WHT, we have detected an extended inclined gaseous disk which is traced up to a distance of about 3.5 kpc from the center, with a spin approximately opposite to the spin of the stellar disk. The galaxy images in the H-alpha and [NII]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 that is absent in the stellar disk of the galaxy is clearly seen in the brightness distribution of ionized-gas lines (H-alpha and [NII] from the MaNGaL data and [OIII] from the SAURON data). A complex analysis of both the Lick index distribution along the radius and of 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, perhaps, for the last 10 Gyr. Thus, the recent external-gas accretion detected in NGC 4143 from its kinematics, was not accompanied by star formation, probably, due to an inclined direction of the gas inflow onto the disk.