S119: a new Luminous Blue Variable?

Summary

Introduction

The LMC star S119 is a member of the group of Ofpe/WN9 stars listed by Bohannan and Walborn (1989). The Ofpe/WN9 category, first defined by Walborn (1982), identifies peculiar supergiants whose spectra combine the typical Of characteristic emission lines of He II and N III with equally strong lower ionization emission features, such as those of He I and N II, and are believed to represent a transition phase in the evolution between massive O stars and WR stars.

High Resolution Echelle Observations

We have observed S119 with the high resolution echelle spectrograph EMMI, coupled to the NTT, ESO La Silla, on September 18, 1991. The spectra cover the wavelength range 4100Å- 7800Å, with a spectral resolution of 0.089 Å/pixel at 6563 Å. The selected slit width was 1.5″ × 5″, with a plate scale on the detector of 0.345″/pixel. In the spectrum, previously undetected nebular lines of Hα, Hβ, [NII], [SII] appear strong and spatially extended, an indication that S119 is surrounded by a bright gaseous nebula. We detect clear splitting of all the observed nebular lines. In Figure 1 we show the radial velocity map obtained from the [NII] 6583 Å line profile. During the observation the slit was oriented EW, and the star was not centered in the aperture, so that only the eastern portion of the nebula lies completely within the slit, while the western region is marginally covered (≃ 2″).