Photometric properties of the Local Volume dwarf galaxies^★

We present surface photometry and metallicity measurements for 104 nearby dwarf galaxies imaged with the Advanced Camera for Surveys and Wide Field and Planetary Camera 2 aboard the Hubble Space Telescope. In addition, we carried out photometry for 26 galaxies of the sample and for Sextans B on images of the Sloan Digital Sky Survey. Our sample comprises dwarf spheroidal, irregular and transition type galaxies located within ∼10 Mpc in the field and in nearby groups: M81, Centaurus A, Sculptor and Canes Venatici I cloud. It is found that the early-type galaxies have on average higher metallicity at a given luminosity in comparison to the late-type objects. Dwarf galaxies with M_B≥−12 to −13 mag deviate towards larger scalelengths from the scalelength–luminosity relation common for spiral galaxies, h∝L^0.5_B. The following correlations between fundamental parameters of the galaxies are consistent with expectations if there is pronounced gas loss through galactic winds: (1) between the luminosity of early-type dwarf galaxies and the mean metallicity of constituent red giant branch stars, Z∼L^0.4, (2) between mean surface brightness within the 25 mag arcsec⁻² isophote and the corresponding absolute magnitude in the V and I bands, SB ₂₅∼ 0.3M₂₅ and (3) between the central surface brightness (or effective surface brightness) and integrated absolute magnitude of galaxies in the V and I bands, SB₀∼ 0.5M_L, SB _e∼ 0.5 M_e. The knowledge of basic photometric parameters for a large sample of dwarf galaxies is essential for a better understanding of their evolution.