The Formation Conditions of the Wide Binary Class 0 Protostars within
  BHR 71
  We present a characterization of the binary protostar system that is forming
within a dense core in the isolated dark cloud BHR71. The pair of protostars,
IRS1 and IRS2, are both in the Class 0 phase, determined from observations that
resolve the sources from 1 um out to 250 um and from 1.3 mm to 1.3cm. The
resolved observations enable the luminosities of IRS1 and IRS2 to be
independently measured (14.7 and 1.7L_sun, respectively), in addition to the
bolometric temperatures 68~K, and 38~K, respectively. The surrounding core was
mapped in NH3 (1,1) with the Parkes radio telescope, and followed with
higher-resolution observations from ATCA in NH3 (1,1) and 1.3cm continuum. The
protostars were then further characterized with ALMA observations in the 1.3~mm
continuum along with N2D+ (J=3-2), 12CO, 13CO, and C18O (J=2-1) molecular
lines. The Parkes observations find evidence for a velocity gradient across the
core surrounding the two protostars, while ATCA reveals more complex velocity
structure toward the protostars within the large-scale gradient. The ALMA
observations then reveal that the two protostars are at the same velocity in
C18O, and N2H+ exhibits a similar velocity structure as NH3. However, the C18O
kinematics reveal that the rotation on scales $<$1000~AU around IRS1 and IRS2
are in opposite directions. Taken with the lack of a systematic velocity
difference between the pair, it is unlikely that their formation resulted from
rotational fragmentation. We instead conclude that the binary system most
likely formed via turbulent fragmentation of the core.
