Our changing view of the blue compact dwarf NGC 2915

TL;DR

This study presents high-resolution HI observations of NGC 2915, revealing complex gas dynamics, evidence of stellar winds, and potential gas infall, offering new insights into the galaxy's structure and evolution.

Contribution

It provides detailed HI kinematic maps and models of NGC 2915, including the first possible evidence of gas infall in a low-mass galaxy.

Findings

Detection of non-circular gas motions in the galaxy

Modeling of a rotating, expanding gas torus explains inner HI features

Possible evidence for a gas infall event in a low-mass galaxy

Abstract

Results from new HI synthesis observations of the nearby blue compact dwarf galaxy, NGC 2915, carried out on the Australian Telescope Compact Array are presented. High resolution HI moment maps for the galaxy reveal complex HI distributions and kinematics. The presence of large non-circular velocity components within the gas at inner radii is revealed. The central gas dynamics are consistent with the simple scenario in which winds from high-mass stars are expelling the gas outwards from the centre of the galaxy. A model in which the central region is treated as a rotating, expanding gas torus is able to reproduce the inner HI morphology and kinematics of NGC 2915. We also find intriguing evidence for a gas infall event which, if confirmed, would be the first such evidence for a low-mass system.