  We present the results of Very Large Array NH$_{3}$ $(J,K)=(1,1)$ and $(2,2)$
observations of the HH 111/HH 121 protostellar system. HH 111, with a
spectacular collimated optical jet, is one of the most well-known Herbig-Haro
objects. We report the detection of a new source (NH$_{3}-$S) in the vicinity
of HH 111/HH 121 ($\sim$0.03 pc from the HH 111 jet source) in two epochs of
the ammonia observations. This constitutes the first detection of this source,
in a region which has been thoroughly covered previously by both continuum and
spectral line interferometric observations. We study the kinematic and physical
properties of HH 111 and the newly discovered NH$_{3}-$S. We also use HCO$^{+}$
and HCN $(J=4-3)$ data obtained with the James Clerk Maxwell Telescope and
archival Atacama Large Millimeter/submillimeter Array $^{13}$CO, $^{12}$CO, and
C$^{18}$O $(J=2-1)$, N$_2$D$^{+}$ $(J=3-2)$, and $^{13}$CS $(J=5-4)$ data to
gain insight into the nature of NH$_{3}-$S. The chemical structure of NH$_3-$S
shows evidence for "selective freeze-out", an inherent characteristic of dense
cold cores. The inner part of NH$_3-$S shows subsonic non-thermal velocity
dispersions indicating a "coherent core", while they increase in the direction
of the jets. Archival near- to far-infrared data show no indication of any
embedded source in NH$_3-$S. The properties of NH$_3-$S and its location in the
infrared dark cloud suggest that it is a starless core located in a turbulent
medium with turbulence induced by Herbig-Haro jets and associated outflows.
More data is needed to fully understand the physical and chemical properties of
NH$_3-$S and if/how its evolution is affected by nearby jets.
