Spectral Energy Distributions of Be and Other Massive Stars

Abstract

ABSTRACT. We present spectrophotometric data from 0.4 μm to 4.2 μm for bright, northern sky, Be stars and several other types of massive stars. Our goal is to use these data with ongoing high-angular-resolution interferometric observations to model the density structure and sky orientation of the gas surrounding these stars. We also present a montage of the Hα and near-infrared emission lines that form in Be star disks. We find that a simplified measurement of the IR excess flux appears to be correlated with the strength of emission lines from high level transitions of hydrogen. This suggests that the near-IR continuum and upper level line fluxes both form in the inner part of the disk, close to the star.

Evidence of Dissipation of Circumstellar Disks from L-band Spectra of Bright Galactic Be Stars

“…Lenorzer et al (2002) examined the ISO spectra of this star and found that their line intensity ratios were closer to the optically thick case, implying opaque lines and a disk-like envelope. Touhami et al (2010) also reported an infrared spectrum of γ Cas, with similar characteristics to those mentioned by previous authors.…”

“…Infrared spectroscopic studies of Be stars have shown that some of these spectra display plenty of hydrogen emission lines that are a result of recombination processes. Particularly, in the L-band, centered in 3.5 μm, there are notorious emission lines of Brackett, Pfund, and Humphreys hydrogen series (Sellgren & Smith 1992;Hony et al 2000;Lenorzer et al 2002;Mennickent et al 2009;Granada et al 2010;Touhami et al 2010). Mennickent et al (2009) obtained L-band spectra of 13 outbursting Be stars through use of the ISAAC/VLT facility, with a resolving power of 1200.…”

“…They concluded that infrared spectroscopy is an ideal tool for studying the structure and evolution of the CDS, in particular, the innermost parts of it, and to test models on the formation mechanisms of the disks. Touhami et al (2010) performed an analysis of optical and infrared spectrophotometric observations of Northern Galactic Be stars, in a wavelength range from 0.4 μm to 4.2 μm, obtained in 2006 and 2008. The optical data were obtained with NOAO Kitt Peak National Observatory Coudé feed telescope, while the infrared data were taken with the NASA Infrared Telescope Facility and SpeX crossdispersed spectrograph and with the Mimir camera/ spectrograph at the Perkins Telescope at Lowell Observatory.…”

Gamma Cas Stars as Be+White Dwarf Binary Systems

“…We caution that the estimates in Table 1 do not account for the possible added flux from disks around both components. Be star disks produce a continuum excess that grows with wavelength and may change the flux from the Be star and its decretion disk by as much as 0.3 mag in the H band (Touhami et al 2010). This would increase the magnitude difference between the Be star and its companion by the same amount.…”

Modeling Circumstellar Disks of B-Type Stars With Observations From the Palomar Testbed Interferometer

“…The infrared excesses are believed to originate in the densest region of the disk near the star and in and near the equatorial plane (Touhami et al 2010). Therefore, since the hydro-on models provide a self-consistent density and temperature distribution, especially important for the densest regions, the hydro-on models are expected to provide a more realistic representation of the physical conditions in the dense gas.…”