The HI Chronicles of LITTLE THINGS BCDS III: Gas Clouds in and around
  Mrk 178, VII Zw 403, AND NGC 3738
  In most blue compact dwarf (BCD) galaxies, it remains unclear what triggers
their bursts of star formation. We study the HI of three relatively isolated
BCDs, Mrk 178, VII Zw 403, and NGC 3738, in detail to look for signatures of
star formation triggers, such as gas cloud consumption, dwarf-dwarf mergers,
and interactions with companions. High angular and velocity resolution atomic
hydrogen (H I) data from the Very Large Array (VLA) dwarf galaxy HI survey,
Local Irregulars That Trace Luminosity Extremes, The HI Nearby Galaxy Survey
(LITTLE THINGS), allows us to study the detailed kinematics and morphologies of
the BCDs in HI. We also present high sensitivity HI maps from the NRAO Green
Bank Telescope (GBT) of each BCD to search their surrounding regions for
extended tenuous emission or companions. The GBT data do not show any distinct
galaxies obviously interacting with the BCDs. The VLA data indicate several
possible star formation triggers in these BCDs. Mrk 178 likely has a gas cloud
impacting the southeast end of its disk or it is experiencing ram pressure
stripping. VII Zw 403 has a large gas cloud in its foreground or background
that shows evidence of accreting onto the disk. NGC 3738 has several possible
explanations for its stellar morphology and H I morphology and kinematics: an
advanced merger, strong stellar feedback, or ram pressure stripping. Although
apparently isolated, the HI data of all three BCDs indicate that they may be
interacting with their environments, which could be triggering their bursts of
star formation.
