Statistics and properties of H II regions in NGC 6814

Abstract

We present a new Halpha image of high quality of the grand-design galaxy NGC 6814, and describe statistical properties of the H II region population. We have determined positions, angular sizes, and calibrated fluxes of 735 individual H II regions. We construct luminosity functions (LFs) for the complete sample, separately for arm and interarm regions, and for H II regions within and outside the limiting radius corresponding to the bright optical disk. The slope of the LF for the complete sample agrees well with values published for other Sbc and Sc galaxies. LFs for H II regions in the arms, in the interarm regions, in the inner part, and in the outer part of the galaxy all have the same slopes. We show and discuss the diameter distribution of the H II regions, both for the complete sample and for the separate arm, interarm, inner, and outer disk samples. There is no evidence for a different population of H II regions in the spiral arms, nor is there evidence for the existence of a significant population of density-bounded H II regions. We discuss implications for massive star forming processes in this galaxy, and discuss possible differences from other grand-design spirals.