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arXiv · astro-ph/0206275

More evidence for hidden spiral and bar features in bright early-type dwarf galaxies

Fabio D. Barazza·Bruno Binggeli·Helmut Jerjen
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Abstract

Following the discovery of spiral structure in IC3328 (Jerjen et al.~2000), we present further evidence that a sizable fraction of bright early-type dwarfs in the Virgo cluster are genuine disk galaxies, or are hosting a disk component. Among a sample of 23 nucleated dwarf ellipticals and dS0s observed with the Very Large Telescope in $B$ and $R$, we found another four systems exhibiting non-axisymmetric structures, such as a bar and/or spiral arms, indicative of a disk (IC0783, IC3349, NGC4431, IC3468). Particularly remarkable are the two-armed spiral pattern in IC0783 and the bar and trailing arms in NGC4431. For both galaxies the disk nature has recently been confirmed by a rotation velocity measurement (Simien & Prugniel 2002). Our photometric search is based on a Fourier decomposition method and a specific version of unsharp masking. Some ``early-type'' dwarfs in the Virgo cluster seem to be former late-type galaxies which were transformed to early-type morphology, e.g. by ``harassment'', during their infall to the cluster, while maintaining part of their disk structure.

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Fabio D. Barazza, Bruno Binggeli, Helmut Jerjen. 2002-06-17. More evidence for hidden spiral and bar features in bright early-type dwarf galaxies. https://doi.org/10.1051/0004-6361%3A20020875

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