We examine the evolution of residual gas within tidally-limited dwarf galaxies and globular clusters. In systems where the gas sound speed exceeds about 10% of the central velocity dispersion, hydrostatic equilibrium causes the gas to have significant density at the tidal radius. In contrast to the stellar component, gas particles relax rapidly in response to mass loss. Gas lost through the Lag...

We have detected the H92α radio recombination line from two dwarf starburst galaxies, NGC 5253 and He 2-10, using the Very Large Array. Both the line data as well as the radio continuum data are used to model the properties of the ionized gas in the centers of these galaxies. We consider a multi-density model for radio recombination lines and show why previous models, which were based on the as...

In order to examine how narrow emission-line flux ratios depend on the Seyfert type, we compiled various narrow emission-line flux ratios of 355 Seyfert galaxies from the literature. We present in this paper that the intensity of the high-ionization emission lines, [Fe vii]λ6087, [Fe x]λ6374 and [Ne v]λ3426, tend to be stronger in Seyfert 1 galaxies than in Seyfert 2 galaxies. In addition to th...

We present deep JHK images of I Zw 18, the most metal-deficient Blue Compact Dwarf (BCD) galaxy known, and analyze them in conjunction with archival HST/WFPC2 optical images. To investigate the stellar populations, we have divided the main body of I Zw18 into eight regions, and fit the optical, near-infrared (NIR), and hybrid optical-NIR colors of these and the C component with evolutionary syn...