| Abstract | We present the results of an investigation into the morphology and dynamics of ionized gas in the bulge of the gas-rich S0 galaxy NGC 5102. We show that the bulge of NGC 5102 contains a ring of ionized gas, 1.3 kpc in diameter, which is centered well away from the nucleus. Through spectroscopy and [O III] λ5007 imaging, we show that the gas is excited by a low-velocity shock, which varies from ~50 to ~70 km s^-1^ along the ring. Fabry-Perot images in Hα confirm that the gas is moving slowly, and suggest that the structure is a supershell, ~10^7^ yr old. This age is significantly younger than the galaxy's nuclear starburst, which is ~2 x 10^8^ yr old. We also use our [O III] λ5007 images to identify planetary nebulae (PNs) in the bulge and inner disk of NGC 5102. Using the planetary nebula luminosity function, we derive a distance modulus to the galaxy of (m - M)_0_ = 27.47_- 0.27_^+0.18^, or 3.1_-0.4_^+0.3^ Mpc, confirming its membership in the NGC 5128 group. Our derived value of 47.2_-9.2_^+12.2^ x 10^-9^ for the bolometric luminosity-specific PN density, α_2.5_, is higher than that observed for the bulge of M31 or the giant ellipticals of the Virgo Cluster, but not significantly different from that found for the small, normal ellipticals NGC 3377 or M32. The high value for α_2.5_ suggests that virtually all of NGC 5102's stars will someday evolve through the planetary nebula stage. |
