SMA observations towards the compact, short-lived bipolar water maser
  outflow in the LkH{\alpha} 234 region
  We present Submillimeter Array (SMA) 1.35 mm subarcsecond angular resolution
observations toward the LkH{\alpha} 234 intermediate-mass star-forming region.
The dust emission arises from a filamentary structure of $\sim$5 arcsec
($\sim$4500 au) enclosing VLA 1-3 and MM 1, perpendicular to the different
outflows detected in the region. The most evolved objects are located at the
southeastern edge of the dust filamentary structure and the youngest ones at
the northeastern edge. The circumstellar structures around VLA 1, VLA 3, and MM
1 have radii between $\sim$200 and $\sim$375 au and masses in the
$\sim$0.08-0.3 M$_{\odot}$ range. The 1.35 mm emission of VLA 2 arises from an
unresolved (r$< 135$ au) circumstellar disk with a mass of $\sim$0.02
M$_{\odot}$. This source is powering a compact ($\sim$4000 au), low radial
velocity ($\sim$7 km s$^{-1}$) SiO bipolar outflow, close to the plane of the
sky. We conclude that this outflow is the "large-scale" counterpart of the
short-lived, episodic, bipolar outflow observed through H$_2$O masers at much
smaller scales ($\sim $180 au), and that has been created by the accumulation
of the ejection of several episodic collimated events of material. The
circumstellar gas around VLA 2 and VLA 3 is hot ($\sim$130 K) and exhibits
velocity gradients that could trace rotation. There is a bridge of warm and
dense molecular gas connecting VLA 2 and VLA 3. We discuss the possibility that
this bridge could trace a stream of gas between VLA 3 and VLA 2, increasing the
accretion rate onto VLA 2 to explain why this source has an important outflow
activity.
