  VLA and Parkes 64 m radiotelescope 21-cm observations of the starburst dwarf
galaxy NGC 5253 reveal a multi-component non-axisymmetric HI distribution. The
component associated with the stellar body shows evidence for a small amount of
rotational support aligned with the major axis, in agreement with optically
measured kinematics and consistent with the small galaxian mass. Approximately
20-30% of the HI emission is associated with a second component, an HI "plume"
extending along the optical minor axis to the southeast. We consider outflow,
inflow, and tidal origins for this feature. Outflow appears improbable, inflow
is a possibility, and tidal debris is most consistent with the observations.
These observations also reveal a filamentary third component that includes an
800 pc diameter HI shell or bubble to the west of the nucleus, coinciding with
an Halpha shell. The mass of HI in the shell may be as large as ~4x10^6 Msun.
This large mass, coupled with the lack of expansion signatures in the neutral
and ionized gas (v<30 km/s), suggests that this feature may be an example of a
starburst-blown bubble stalled by interaction with a massive neutral envelope.
Many other HI kinematic features closely resemble those seen in Halpha emission
from the ionized gas, supporting the interpretation of neutral and ionized gas
outflow at velocities of ~30 km/s. Comparison between extinction estimates from
the Balmer emission-line decrement and the HI column densities suggest a
gas-to-dust ratio 2-3 times the Galactic value in this low-metallicity (Z=1/4
Zsun) galaxy.
