We combine high-quality IFU data with a new set of numerical simulations to study low-mass early type galaxies (dEs) in dense environments. Our earlier study of dEs in the Virgo cluster has produced the first large-scale maps of kinematic and stellar population properties of dEs in those environments (Ryś et al. 2013, 2014, 2015). A quantitative discrimination between various (trans)formation processes proposed for these objects is, however, a complex issue, requiring a priori assumptions about the progenitors of galaxies we observe and study today. To bridge this gap between observations and theoretical predictions, we use the expertise gained in the IFU data analysis to look “through the eye of SAURON” at our new suite of high-resolution N-body simulations of dEs in the Virgo cluster. Mimicking the observers perspective as closely as possible, we can also indicate the existing instrumental and viewer limitations regarding what we are/are not able to detect as observers.

Early-type dwarf galaxies dominate cluster populations, but their formation and evolutionary histories are poorly understood. The ALFALFA (Arecibo Legacy Fast ALFA) survey has completed observations of the Virgo Cluster in the declination range of 6 – 16 degrees. Less than 2% of the early-type dwarf population is detected, a significantly lower fraction than reported in previous papers based on more limited samples. In contrast ~30% of the irregular/BCD dwarf population is detected. The detected early-type galaxies tend to be located in the outer regions of the cluster, with a concentration in the direction of the M Cloud. Many show evidence for ongoing/recent star formation. Galaxies such as these may be undergoing morphological transition due to cluster environmental effects.

HI observations of the Virgo Cluster pair NGC 4532/DDO 137, conducted as part of the Arecibo Legacy Fast ALFA Survey, reveal an HI feature extending ~500kpc to the southwest. The structure has a total mass of up to 7 x 108M⊙, equivalent to 10% of the pair HI mass. Optical R imaging reveals no counterparts to a level of 26.5 mag arcsec−2. The structure is likely the result of galaxy harassment.