On the nature of IC 3328, an early-type dwarf galaxy with weak spiral structure

Various early-type dwarf galaxies with disk features have been identified in the Virgo cluster, including objects that display weak grand-design spiral arms despite being devoid of gas. Are these still related to the classical dEs, or are they a continuation of ordinary spiral galaxies? Kinematical information of acceptable quality is available for one of these galaxies, IC 3328. We investigated its dynamical configuration, taking the effect of asymmetric drift into account, and using the Toomre parameter, as well as density wave considerations. The derived mass-to-light ratios and rotational velocities indicate a significant dynamically hot component in addition to the disk. However, any unambiguous conclusions will need to await further data for this and other early-type dwarfs with spiral structure.