SIMBAD references

Long-slit spectroscopy has been obtained for a sample of 22 blue dwarf galaxies selected in the direction of the Virgo Cluster, as part of a larger sample of Virgo blue dwarf galaxies for which deep Hα imaging has been collected. Most of the galaxies in the present sample are classified as BCDs or dwarf Irregulars in the Virgo Cluster Catalog. Line fluxes, Hβ equivalent widths, extinction coefficients, spatial emission profiles, ionization structure, and physical conditions are presented for each galaxy. Chemical abundances have been derived either using a direct determination of the electron temperature or after detailed examination of the predictions of different abundance calibrations. The oxygen abundances derived for the sample of Virgo dwarf galaxies span the range 7.6≤12+log(O/H)≤8.9, and the corresponding nitrogen-to-oxygen abundance ratio ranges from values typical of low-metallicity field BCD galaxies to near solar.