FCC046: a candidate gaseous polar ring dwarf elliptical galaxy in the Fornax Cluster

Abstract

FCC046 is a Fornax Cluster dwarf elliptical galaxy. Optical observations have shown that this galaxy, besides an old and metal-poor stellar population, also contains a very young centrally concentrated population and is actively forming stars, albeit at a very low level. Here, we report on 21cm observations of FCC046 with the Australia Telescope Compact Array (ATCA) which we conducted in the course of a small survey of Fornax Cluster early-type dwarf galaxies. We have discovered a ~10^7 Mo HI cloud surrounding FCC046. We show that the presence of this significant gas reservoir offers a concise explanation for this galaxy's optical morphological and kinematical properties. Surprisingly, the HI gas, as evidenced by its morphology and its rotational motion around the galaxy's optical major axis, is kinematically decoupled from the galaxy's stellar body. This is the first time such a ring of gaseous material in minor-axis rotation is discovered around a dwarf galaxy.

5 pages, 4 figures, published in Astrophysical Journal Letters

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• Abundance ratios and IMF slope in the dwarf elliptical galaxy NGC~1396 with MUSE
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• Young stellar populations in early-type dwarf galaxies; occurrence, radial extent and scaling relations
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• HI in Virgo's "Red and Dead" Dwarf Ellipticals - A Tidal Tail and Central Star Formation
• Kinematics of dwarf galaxies in gas-rich groups, and the survival and detectability of tidal dwarf galaxies
• The discovery of blue-cored dwarf early-type galaxies in isolated environments
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• Chemodynamic evidence of pristine gas accretion in the void galaxy VGS 12