The NGC 1614 Interacting Galaxy: Molecular Gas Feeding a "Ring of Fire"
  Minor mergers frequently occur between giant and gas-rich low mass galaxies
and can provide significant amounts of interstellar matter to refuel star
formation and power AGN in the giant systems. Major starbursts and/or AGN
result when fresh gas is transported and compressed in the central regions of
the giant galaxy. This is the situation in NGC1614, whose molecular medium we
explore at half arcsecond angular resolution through our observations of
12CO(2-1) emission using the SMA. We compare our maps with optical and Pa
alpha, HST and high angular resolution radio continuum images to study the
relationships between dense molecular gas and the starburst region. The most
intense CO emission occurs in a partial ring with ~230pc radius around the
center, with an extension to the north-west into the dust lane that contains
diffuse molecular gas. We resolve 10 GMAs in the ring which has an integrated
molecular mass of ~8x10^8M_sun. Our observations filter out a large part of the
CO(1-0) emission mapped at shorter spacings, indicating that most of the
molecular gas is diffuse and that GMAs only exist near and within the
circumnuclear ring. The molecular ring is uneven with most of the mass on the
western side, which also contains GMAs extending into a pronounced tidal dust
lane. The spatial and kinematic patterns suggest that the northwest extension
of the ring is a cosmic umbilical cord that is feeding molecular gas associated
with the dust lane and tidal debris into the nuclear ring. The astrophysical
process for producing a ring structure is not fully understood, but the
presence of numerous GMAs suggests an orbit crowding or resonance phenomenon.
There is some evidence that star formation is progressing radially outwards
within the ring, indicating that a self-triggering mechanism may also affect
these processes.
