The optical emission nebulae in the vicinity of WR 48 (Theta Mus); True
  Wolf-Rayet ejecta or unconnected supernova remnant?
  During searches for new optical Galactic supernova remnants (SNRs) in the
high resolution, high sensitivity Anglo-Australian Observatory/United Kingdom
Schmidt Telescope (AAO/UKST) HAlpha survey of the southern Galactic plane, we
uncovered a variety of filamentary and more diffuse, extensive nebular
structures in the vicinity of Wolf-Rayet (WR) star 48 (Theta Muscae), only some
of which were previously recognised. We used the double-beam spectrograph of
the Mount Stromlo and Siding Spring Observatory (MSSSO) 2.3-m to obtain low and
mid resolution spectra of selected new filaments and structures in this region.
Despite spectral similarities between the optical spectra of WR star shells and
SNRs, a careful assessment of the new spectral and morphological evidence from
our deep HAlpha imagery suggests that the putative shell of Theta Mus is not a
WR shell at all, as has been commonly accepted, but is rather part of a more
complex area of large-scale overlapping nebulosities in the general field of
the WR star. The emission comprises a possible new optical supernova remnant
and a likely series of complex H II regions. Finally, we present the intriguing
detection of apparent collimated, directly opposing, ionized outflows close to
Theta Mus itself which appears unique among such stars. Although possible
artifacts or a temporary phenomenon monitoring of the star is recommended.
