A kinematical study of the dwarf irregular galaxy NGC 1569 and its supernova remnants

We present Fabry-Perot observations in the H alpha and [S ii] lines to study the kinematics of the Magellanic-type dwarf irregular galaxy NGC 1569, these observations allowed us to compute the H alpha velocity field of this galaxy. Doing a detailed analysis of the velocity along the line of sight and H alpha velocity profiles, we identified the origin of most of the motions in the innermost parts of the galaxy and discarded the possibility of deriving a rotation curve that traces the gravitational well of the galaxy. We analysed the kinematics of the ionized gas around 31 supernova remnants previously detected in NGC 1569 by other authors, in optical and radio emission. We found that the H alpha velocity profiles of the supernova remnants are complex indicating the presence of shocks. Fitting these profiles with several Gaussian functions, we computed their expansion velocities which rank from 87 to 188 km s(-1) confirming they are supernova remnants. Also, we determined the physical properties such as electron density, mechanical energy, and kinematic age for 30 of the 31 supernova remnants and found they are in the radiative phase with an energy range from 1 to 39 x 10(50) erg s(-1) and an age from 2.3 to 8.9 x 10(4) yr. Finally, we estimated the Surface Brightness-Diameter (sigma-D) relation for NGC 1569 and obtained a slope beta = 1.26 +/- 0.2, comparable with the beta value obtained for supernova remnants in galaxies M31 and M33.

Automated summary

In this study, we used Fabry-Perot observations to investigate the kinematics of NGC 1569 and computed its H alpha velocity field. Our analysis identified the origin of most motions in the galaxy and ruled out the possibility of deriving a rotation curve. We also analyzed the kinematics of supernova remnants in NGC 1569 and determined their physical properties.