Decreasing Density Gradients in Circumnuclear HII Regions of Barred Galaxies NGC 1022, 1326 & 4314

Abstract

A re-analysis of the radio continuum emission from circumnuclear regions of the barred galaxies NGC 1022, 1326 & 4314 is presented. The spatial distributions of Halpha and radio continuum are similar and suggest the existence of several giant HII regions in the circumnuclear zone. The spectral indices of the HII regions, obtained with similar angular resolution and at three different wavelengths, indicate that in all three galaxies, the spectral index, alpha^6_2 >-0.1. This result suggests the existence of giant HII regions with decreasing density gradients. The average density stratifications of these HII regions could be approximated by power-laws of the form n_e~r^-w, with exponents in the range 1.6 < w < 2.4.