| Abstract | We present ultraviolet-integrated and azimuthally averaged surface photometric properties of a sample of 44 dwarf irregular (dIm), blue compact dwarf, and Sm galaxies measured from archival near-ultraviolet (NUV) and far-ultraviolet (FUV) images obtained with the Galaxy Evolution Explorer (GALEX). We compare the UV to Hα and V-band properties and convert FUV, Hα, and V-band luminosities into star formation rates (SFRs). We also model the star formation history from colors and compare the integrated SFRs and SFR profiles with radius for these methods. In most galaxies, the UV photometry extends beyond Hα in radius, providing a better measure of the star formation activity in the outer disks. The Hα appears to be lacking in the outer disk because of faintness in low-density gas. The FUV and V-band profiles are continuous with radius, although they sometimes have a kink from a double exponential disk. There is no obvious difference in star formation properties between the inner and outer disks. No disk edges have been observed, even to stellar surface densities as low as 0.1 M sun pc-2 and SFRs as low as 10-4 M sun yr-1 kpc-2. Galaxies with low H I to luminosity ratios have relatively low FUV compared to V-band emission in the outer parts, suggesting a cessation of star formation there. Galaxies with relatively high H I apparently have fluctuating star formation with a gigayear timescale. Based on observations made with the NASA Galaxy Evolution Explorer (GALEX). GALEX is operated for NASA by the California Institute of Technology under NASA contract NAS5-98034. |
