Photometric properties of Kiso ultraviolet-excess galaxies in the Lynx-Ursa Major region

We have performed a systematic study of several regions in the sky where th e number of galaxies exhibiting star formation (SF) activity is greater tha n average. We used Kiso ultraviolet-excess galaxies (KUGs) as our SE-enhanc ed sample. By statistically comparing the KUG and non-RUG distributions, we discovered four RUG-rich regions with sizes of similar to 10 degrees x 10 degrees. One of these regions corresponds spatially to a filament of length similar to 60 h(-1) Mpc in the Lynx-Ursa Major region (alpha similar to 9( h)-10(h), delta similar to 42 degrees-48 degrees). We call this "the Lynx-U rsa Major (LUM) filament." We obtained V(RI)(C) surface photometry of 11 of the KUGs in the LUM filament and used these to investigate the integrated colors, the distribution of SF regions, the morphologies, and the local env ironments. We found that these KUGs consist of distorted spiral galaxies an d compact galaxies with blue colors. Their star formation occurs in the ent ire disk and is not confined to just the central regions. The colors of the SF regions imply that active star formation in the spiral galaxies occurre d 10(7-8) yr ago, while that in the compact objects occurred 10(6-7) yr ago . Though the photometric characteristics of these KUGs are similar to those of-interacting galaxies or mergers, most of these KUGs do not show direct evidence of merger processes.