  SuWt 2 is a planetary nebula consisting of a bright ring-like waist from
which protrude faint extended lobes - a morphology believed to be typical of
progenitors which have experienced a close-binary evolution. Previous
observations of NSV 19992, the star at the projected centre of SuWt 2, have
found it to comprise two A-type stars in a 4.9 day eclipsing orbit, neither of
which could be the nebular progenitor. Radial velocity studies provided a hint
that the systemic velocity of this double A-type binary might be varying over
time, suggesting the presence of a third component hypothesised to be the
nebular progenitor. Here, we present an extensive radial velocity monitoring
study of NSV 19992, performed with the high-resolution echelle spectrograph
UVES mounted on ESO's VLT, in order to constrain the possible variation in the
systemic velocity of the A-type binary and its relation to the progenitor of
SuWt 2. The observations, acquired over a period of approximately one year,
show no evidence of variability in the systemic velocity of NSV 19992.
Combining these new observations with previous high-resolution spectroscopy
demonstrates that the systemic velocity is also stable over much longer periods
and, moreover, is distinct from that of SuWt 2, strongly indicating that the
two are not associated. We conclude that NSV 19992 is merely a field star
system, by chance lying in the same line of sight as the nebular centre, and
that it bares no relation to SuWt 2 or its, as yet unidentified, central
star(s).
