A deep near-infrared spectroscopic survey of the Scutum-Crux arm for
  Wolf-Rayet stars
  We present an NTT/SOFI spectroscopic survey of infrared selected Wolf-Rayet
candidates in the Scutum-Crux spiral arm (298 < l < 340, |b| < 0.5). We
obtained near-IR spectra of 127 candidates, revealing 17 Wolf-Rayet stars - a
~13% success rate - of which 16 are newly identified here. The majority of the
new Wolf-Rayet stars are classified as narrow-lined WN5-7 stars, with 2
broad-lined WN4-6 stars and 3 WC6-8 stars. The new stars, with distances
estimated from previous absolute magnitude calibrations, have no obvious
association with the Scutum-Crux arm. Refined near-infrared (YHJK)
classification criteria based on over a hundred Galactic and Magellanic Cloud
WR stars, providing diagnostics for hydrogen in WN stars, plus the
identification of WO stars and intermediate WN/C stars. Finally, we find that
only a quarter of WR stars in the survey region are associated with star
clusters and/or HII regions, with similar statistics found for Luminous Blue
Variables in the Milky Way. The relative isolation of evolved massive stars is
discussed, together with the significance of the co-location of LBVs and WR
stars in young star clusters.
