A contracting circumbinary molecular ring with an inner cavity of about
  140 AU around Ori 139-409
  Sensitive and subarcsecond resolution ($\sim$ 0.7\arcsec) CH$_3$OH(7$_{-2,6}$
$\to$ 6$_{-2,5}$) line and 890 $\mu$m continuum observations made with the
Submillimeter Array (SMA) towards the hot molecular circumbinary ring
associated with the young multiple star Ori 139-409 are presented. The
CH$_3$OH(7$_{-2,6}$ - 6$_{-2,5}$) emission from the ring is well resolved at
this angular resolution revealing an inner cavity with a size of about 140 AU.
A LTE model of a Keplerian disk with an inner cavity of the same size confirms
the presence of this cavity. Additionally, this model suggests that the
circumbinary ring is contracting with a velocity of V$_{inf}$ $\sim$ 1.5 km
s$^{-1}$ toward the binary central compact circumstellar disks reported at a
wavelength of 7 mm. {\bf The inner central cavity seems to be formed by the
tidal effects of the young stars in the middle of the ring.} The ring appears
to be not a stationary object. Furthermore, the infall velocity we determine is
about a factor of 3 slower than the free-fall velocity corresponding to the
dynamical mass. This would correspond to a mass accretion rate of about
10$^{-5}$ M$_\odot$/yr. We found that the dust emission associated with Ori
139-409 appears to be arising from the circumstellar disks with no strong
contribution from the molecular gas ring. A simple comparison with other
classical molecular dusty rings (e.g. GG Tau, UZ Tau, and UY Aur) suggests that
Ori 139-409 could be one of the youngest circumbinary rings reported up to
date. Finally, our results confirm that the circumbinary rings are actively
funneling fresh gas material to the central compact binary circumstellar disks,
i.e. to the protostars in the very early phases of their evolution.
