Program: GN-2013A-Q-78

Several phases in massive star evolution, like luminous blue variables (LBVs) and B[e] supergiants (B[e]SGs) undergo strong, often eruptive mass -loss phases. These stars are deeply embedded in shells, nebulae, or disks, which are cool and dense, and give rise to a complex chemistry, producing molecules and dust. Furthermore, stars in both groups are rare and those identified so far display complex spectra making it difficult to study the kinematics of their circumstellar environment and their mass loss history. To improve the number of stars in both groups and to study their circumstellar medium, we propose to observe a sample of suggested candidates in the near-infrared using GNIRS. The spectral coverage in the K-band encompasses molecular band emission from both 12CO and 13CO and the series of the hydrogen Pfund lines. The absence of CO bands immediately classifies the star as LBV. Objects showing CO emission need to be investigated for the presence of 13CO bands, to properly assign them a B[e]SG state. Detailed modeling of the spectra will provide physical parameters of their environment, which are of vital importance for a better understanding of the mass-loss history of these fundamental objects.