Spectral atlas of massive stars around He i 10830 Å

Abstract

We present a digital atlas of peculiar, high-luminosity massive stars in the near-infrared region (10470-11000 Å) at medium resolution (R ≃ 7000). The spectra are centered around He I 10830 Å, which is formed in the wind of those stars, and is a crucial line to obtain their physical parameters. The instrumental configuration also sampled a rich variety of emission lines of Fe II, Mg II, C I, N I, and Pa γ. Secure identifications for most spectral lines are given, based on synthetic atmosphere models calculated by our group. We also propose that two unidentified absorption features have interstellar and/or circumstellar origin. For the strongest one (10 780 Å) an empirical calibration between E(B - V) and equivalent width is provided. The atlas displays the spectra of massive stars organized in four categories, namely Be stars, OBA Iape (or luminous blue variables, LBV candidates and ex/dormant LBVs), OB supergiants and Wolf-Rayet stars. For comparison, the photospheric spectra of non emission-line stars are presented. Selected LBVs were observed in different epochs from 2001 to 2004, and their spectral variability reveals that some stars, such as η Car, AG Car and HR Car, suffered dramatic spectroscopic changes during this time interval. © ESO 2007.