The Smallest Scale of Hierarchy Survey (SSH) - II. Extended star formation and bar-like features in the dwarf galaxy NGC 3741: recent merger or ongoing gas accretion?

Using Large Binocular Telescope deep imaging data from the Smallest Scale of Hierarchy Survey (SSH) and archival Hubble Space Telescope data, we reveal the presence of two elongated stellar features contiguous to a bar-like stellar structure in the inner regions of the dwarf irregular galaxy NGC 374...

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Main Authors: Annibali, F. (Author), Bacchini, C. (Author), Beccari, G. (Author), Bellazzini, M. (Author), Bisogni, S. (Author), Cignoni, M. (Author), Ciotti, L. (Author), Cusano, F. (Author), Gargiulo, A. (Author), Iorio, G. (Author), Nipoti, C. (Author), Paris, D. (Author), Pascale, R. (Author), Sacchi, E. (Author), Tosi, M. (Author)
Format: Article
Language:English
Published: Oxford University Press 2022
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Summary:Using Large Binocular Telescope deep imaging data from the Smallest Scale of Hierarchy Survey (SSH) and archival Hubble Space Telescope data, we reveal the presence of two elongated stellar features contiguous to a bar-like stellar structure in the inner regions of the dwarf irregular galaxy NGC 3741. These structures are dominated by stars younger than a few hundred Myr and collectively are about twice as extended as the old stellar component. These properties are very unusual for dwarf galaxies in the nearby Universe and difficult to explain by hydro-dynamical simulations. From the analysis of archival 21-cm observations, we find that the young stellar 'bar' coincides with an H i high-density region proposed by previous studies to be a purely gaseous bar; we furthermore confirm radial motions of a few km s-1, compatible with an inflow/outflow, and derive a steeply rising rotation curve and high H i surface density at the centre, indicating a very concentrated mass distribution. We propose that the peculiar properties of the stellar and gaseous components of NGC 3741 may be explained by a recent merger or ongoing gas accretion from the intergalactic medium, which caused gas inflows towards the galaxy centre and triggered star formation a few hundred Myr ago. This event may explain the young and extended stellar features, the bar-like structure, the very extended H i disc and the central H i spiral arms. The high central H i density and the steeply rising rotation curve suggest that NGC 3741 may be the progenitor or the descendant of a starburst dwarf. © 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
Physical Description:14
ISBN:00358711 (ISSN)
DOI:10.1093/mnras/stac541