The supergiant shell with triggered star formation in Irr galaxy IC 2574: neutral and ionized gas kinematics

TL;DR

This study investigates the kinematics of neutral and ionized gas in the supergiant shell of galaxy IC 2574, confirming its expansion velocity, analyzing star formation regions, and identifying a faint diffuse emission, providing insights into the shell's dynamics and star formation processes.

Contribution

It introduces a combined analysis of neutral and ionized gas kinematics using Fabry-Perot and THINGS data, confirming shell expansion and revealing new faint diffuse emission inside the SGS.

Findings

Confirmed SGS expansion velocity of 25 km/s.

Identified a faint diffuse H-alpha emission inside the SGS.

Confirmed the old SNR nature of a radio-identified region.

Abstract

We analyse the ionized gas kinematics in the star formation regions of the supergiant shell (SGS) of the IC 2574 galaxy using observations with the Fabry-Perot interferometer at the 6-m telescope of SAO RAS; the data of the THINGS survey are used to analyze the neutral gas kinematics in the area. We perform the 'derotation' of the H-alpha and HI data cubes and show its efficiency in kinematics analysis. We confirm the SGS expansion velocity 25 km/s obtained by Walter & Brinks (1999) and conclude that the SGS is located at the far side of the galactic disc plane. We determine the expansion velocities, kinematic ages, and the required mechanical energy input rates for four star formation complexes in the walls of the SGS; for the remaining ones we give the limiting values of the above parameters. A comparison with the age and energy input of the complexes' stellar population shows that sufficient energy is fed to all HII regions except one. We discuss in detail the possible nature of this region and that of another one, which was believed to be an SNR according to radio observations. We measured the expansion velocity of the latter and confirm its identification as an old SNR. Our observations allowed us to identify a faint diffuse H-alpha emission inside the SGS which was never observed before.