Spectroscopy and Interferometry of Luminous Blue Variables

TL;DR

This study presents extensive spectroscopic and interferometric observations of luminous blue variables, revealing wind structures, binary interactions, and variability, advancing understanding of their complex stellar environments.

Contribution

It provides new detailed spectroscopic data, discovers wind features, and identifies binary characteristics in LBVs, offering insights into their mass-loss and evolution.

Findings

Detection of discrete absorption components in P Cygni's Hα profile.

Identification of a short-period binary orbit in HDE 326823.

Observation of η Car's recovery post-periastron.

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.