Spectroscopy and Interferometry of Luminous Blue Variables

Abstract

We report on the preliminary results of a three-year monitoring campaign of Galactic and Magellanic LBVs with both moderate and high resolution spectroscopy. We have collected more than 500 moderate-resolution spectra of 20 stars in the red portion of the optical spectrum, which includes the wind-sensitive transitions of H$\alpha$ and He I 5876 and 6678 Angstroms. We summarize our detailed study of 15 years of high resolution H$\alpha$ spectroscopy of the prototypical luminous blue variable, P Cygni. We report on the discovery of discrete absorption components in P Cygni's H$\alpha$ profile, and we discuss their relationship to structure in the wind. These results are compared to our recent high resolution interferometric imaging of the $H$-band emitting region surrounding the star. We discuss recent observations of $\eta$ Car, highlighting its unusual recovery from the previous periastron passage. Our results on HDE 326823 indicate that the star has a short period binary orbit, with Roche Lobe overflow onto an unseen massive companion.