Radio Observations of the Star Formation Activities in the NGC 2024 FIR
  4 Region
  Star formation activities in the NGC 2024 FIR 4 region were studied by
imaging centimeter continuum sources and water maser sources using several
archival data sets from the Very Large Array. The continuum source VLA 9 is
elongated in the northwest-southeast direction, consistent with the FIR 4
bipolar outflow axis, and has a flat spectrum in the 6.2-3.6 cm interval. The
three water maser spots associated with FIR 4 are also distributed along the
outflow axis. One of the spots is located close to VLA 9, and another one is
close to an X-ray source. Examinations of the positions of compact objects in
this region suggest that the FIR 4 cloud core contains a single low-mass
protostar. VLA 9 is the best indicator of the protostellar position. VLA 9 may
be a radio thermal jet driven by this protostar, and it is unlikely that FIR 4
contains a high-mass young stellar object (YSO). A methanol 6.7 GHz maser
source is located close to VLA 9, at a distance of about 100 AU. The FIR 4
protostar must be responsible for the methanol maser action, which suggests
that methanol class II masers are not necessarily excited by high-mass YSOs.
Also discussed are properties of other centimeter continuum sources in the
field of view and the water masers associated with FIR 6n. Some of the
continuum sources are radio thermal jets, and some are magnetically active
young stars.
