Decreasing density gradients in circumnuclear HII regions of barred galaxies NGC 1022, NGC 1326, and NGC 4314

Abstract

A reanalysis of the radio continuum emission from circumnuclear regions of the barred galaxies NGC 1022, NGC 1326, and NGC 4314 is presented. The spatial distributions of Ha and radio continuum are similar and suggest the existence of several giant H II regions in the circumnuclear zone. The spectral indices of the H 11 regions, obtained with similar angular resolution and at three different wavelengths, indicate that in all three galaxies alpha (6)(2) > -0.1. This result suggests the existence of giant H II regions with decreasing density gradients. The average density stratifications of these H 11 regions could be approximated by power laws of the form n(e) proportional to r(-omega), with exponents in the range 1.6 < omega < 2.4.