Evidence of an interaction from resolved stellar populations: the curious case of NGC 1313

Abstract

The galaxy NGC 1313 has attracted the attention of various studies due to the peculiar morphology observed in optical bands, although it is classified as a barred, late-type galaxy with no apparent close-by companions. However, the velocity field suggests an interaction with a satellite companion. Using resolved stellar populations, we study different parts of the galaxy to understand further its morphology. Based on Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) images, we estimated star formation histories by means of the synthetic colour-magnitude diagram method in different areas in the galaxy. Incompleteness limits our analysis to ages younger than ∼100 Myr. Stars in the red and blue He-burning phases are used to trace the distribution of recent star formation. Star formation histories suggest a burst in the south-western region. We support the idea that NGC 1313 is experiencing an interaction with a satellite companion, observed as a tidally disrupted satellite galaxy in the south-west of NGC 1313. However, we do not observe any indication of a perturbation due to the interaction with the satellite galaxy at other locations across the galaxy, suggesting that only a modest-sized companion that did not trigger a global starburst was involved.