The Diffuse Ionized Gas Halo of the Small Magellanic Cloud
  Observations with the Wisconsin H-alpha Mapper (WHAM) reveal a large, diffuse
ionized halo that surrounds the Small Magellanic Cloud (SMC). We present the
first kinematic H-alpha survey of an extended region around the galaxy, from
(l,b) = (289.5,-35.0) to (315.1,-5.3) and covering +90 <= vLSR <= +210 km s-1.
The ionized gas emission extends far beyond the central stellar component of
the galaxy, reaching similar distances to that of the diffuse neutral halo
traced by 21 cm observations. H-alpha emission extends several degrees beyond
the sensitivity of current H I surveys toward smaller Galactic longitudes and
more negative Galactic latitudes. The velocity field of the ionized gas near
the SMC appears similar to to the neutral halo of the galaxy. Using the
observed emission measure as a guide, we estimate the mass of this newly
revealed ionized component to be roughly (0.8 - 1.0) x 10^9 M_sun, which is
comparable to the total neutral mass in the same region of (0.9 - 1.1) x 10^9
M_sun. We find ratios of the total ionized gas mass divided by the total
neutral plus ionized gas mass in three distinct subregions to be: (1) 46%-54%
throughout the SMC and its extended halo, (2) 12%-32% in the SMC Tail that
extends toward the Magellanic Bridge, and (3) 65%-79% in a filament that
extends away from the SMC toward the Magellanic Stream. This newly discovered,
coherent H-alpha filament does not appear to have a well-structured neutral
component and is also not coincident with two previously identified filaments
traced by 21 cm emission within the Stream.
