Observational constraints on the X-ray Bright supergiant B[e] stars LHA 115-S18 \& LHA 120-S 134

Abstract

We present the preliminary results of an ongoing series of spectroscopic observations of the Small Magellanic Cloud star LHA 115-S 18 (S18), which has demonstrated extreme photospheric and spectroscopic variability that, in some respects, is reminiscent of Luminous Blue Variables (LBVs). In contrast to our previously published results, between 2012-2015 S18 remained in an spectral state intermediate between S18's "hot" and "cool" extremes. In conjunction with contemporaneous OGLE-IV photometric monitoring of S18, these data will be used to determine the characteristic timescale of the variability and search for periodicities, in particular binary modulated periodicity. We also present the results of a pilot study of the LMC star LHA 120-S 134.

8 pages, 4 figures, to appear in the proceedings of the SALT Science Conference 2015 (SSC2015), 1-5 June 2015, Stellenbosch Institute of Advanced Study, South Africa, Eds. G. E. Bromage, D. A. H. Buckley, K. N. Hainline, J. Mikołajewska, R. Srianand, E. Wilcots, T. J. Williams