The presence of blue cores in some dwarf early-type galaxies ( dEs ) in galaxy clusters suggests the scenario of late-type galaxy infall and subsequent transformation into red , quiescent dEs .
We present Gemini Multi-Object Spectrographs long-slit spectroscopy of two dEs with blue cores ( dE ( bc ) s ) , EVCC 591 and EVCC 516 , located at the core and outskirt of the Virgo cluster , respectively .
We obtained their internal kinematics along the major axis out to , at least , \sim 1 effective radius .
EVCC 591 shows evidence of a kinematically decoupled core ( KDC ) with a size of 2 \arcsec ( 160 pc ) , exhibiting an inverted pattern for velocity with respect to the main body of its host galaxy .
The rotation curve of the stellar component in the inner region of EVCC 591 is steeper than that in the rest of the galaxy .
On the other hand , overall velocity profiles of stellar and ionized gas components of EVCC 516 show no signature of significant rotation .
The occurrence of a KDC and zero rotation in the internal kinematics along with the central star formation support the scenario of gas-rich dwarf-dwarf mergers in the formation of these two dE ( bc ) s. Furthermore , evolution of dE ( bc ) s in a cluster environment into ordinary dEs with KDCs is possible based on their structural properties .
We suggest that at least some of the dE ( bc ) s in the Virgo cluster were formed through dwarf-dwarf mergers in lower density environments before they subsequently fell into the cluster ; they were then quenched by subsequent effects within the cluster environment .