Searching for star-forming galaxies in the Fornax and Hydra clusters
  The formation and evolution of dwarf galaxies is relatively difficult to
understand because of their faint emission in all regimes that require large
aperture telescopes. We intend to study the evolution of star forming dwarf
galaxies in clusters. We selected Fornax and Hydra clusters to complement our
previous study of Virgo. On the basis of available literature data, we selected
ten star-forming candidates in Fornax and another ten objects in Hydra. We used
Gemini South with GMOS to acquire H-alpha images necessary to detect
star-forming regions in the two galaxy samples. We then performed long-slit
spectroscopy for the brightest six candidates, to derive their chemical
properties. Finally, we employed the VLT with HAWK-I to observe all galaxies in
the K' band to derive their main physical properties. We studied the morphology
of our two samples, finding five objects in Fornax and six in Hydra with
structures consistent with those of star-forming dwarfs, i.e., dwarf irregulars
(dIs) or blue compact dwarfs (BCDs). About four other objects are probably
dwarf spirals, while three objects remained undetected in both visible and near
infrared. On the basis of visible bright emission lines, we derived oxygen
abundances for ten star-forming candidates with values between 8.00 and 8.78.
Most fundamental properties of star-forming galaxies in Fornax and Hydra appear
similar to corresponding properties of dIs and BCDs from Virgo and the Local
Volume (LV). The luminosity-metallicity and metallicity-gas fraction relations
in the LV and Virgo appear to be followed by Fornax and Hydra samples,
suggesting that the chemical evolution of the two clusters seems consistent
with the predictions from the closed box model, although larger samples are
needed to investigate the role of possible environmental effects. (CONTINUED)
