Mid-Infrared Spectra of Be Stars

Abstract

We present the first medium-resolution ($R\sim 600$) mid-infrared (8-13.3\micron) spectra of 11 Be stars. A large number of lines are observed and identified in these spectra, including, as an example, 39 hydrogen recombination lines in the spectrum of $\gamma$ Cas. In the majority of our spectra, all of the observed lines are attributable to hydrogen recombination. Two of the sources, $\beta$ Lyr and MWC 349 also show emission from other species. Both of these objects show evidence of [Ne II] emission, and $\beta$ Lyr also shows evidence of He I emission. We tabulate the effective line strength and line widths for the observed lines, and briefly discuss the physical implications of the observed line series. We also use a simple model of free-free emission to characterize the disks around these sources.