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Description
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) has amassed the largest ever collection of multi-epoch, high-resolution (R~22500), H-band spectra for B-type emission line (Be) stars. These stars were targeted by APOGEE as telluric standard stars and subsequently identified via visual inspection as Be stars based on HI Brackett series emission or shell absorption in addition to otherwise smooth continua and occasionally non-hydrogen emission features. The 128/238 APOGEE Be stars for which emission had never previously been reported serve to increase the total number of known Be stars by ~6%. Because the H band is relatively unexplored compared to other wavelength regimes, we focus here on identification of the H-band lines and analysis of the emission peak velocity separations ({Delta}v_p_) and emission peak intensity ratios (V/R) of the usually double-peaked HI and non-hydrogen emission lines. HI Br11 emission is found to preferentially form in the circumstellar disks at an average distance of ~2.2 stellar radii. Increasing {Delta}v_p_ toward the weaker Br12-Br20 lines suggests these lines are formed interior to Br11. By contrast, the observed IR FeII emission lines present evidence of having significantly larger formation radii; distinctive phase lags between IR FeII and HI Brackett emission lines further supports that these species arise from different radii in Be disks. Several emission lines have been identified for the first time including CI 16895, a prominent feature in the spectra for almost a fifth of the sample and, as inferred from relatively large {Delta}v_p_ compared to the Br11-Br20, a tracer of the inner regions of Be disks. Emission lines at 15760{AA} and 16781{AA} remain unidentified, but usually appear along with and always have similar line profile morphology to FeII 16878. Unlike the typical metallic lines observed for Be stars in the optical, the H-band metallic lines, such as FeII 16878, never exhibit any evidence of shell absorption, even when the HI lines are clearly shell-dominated. The first known example of a quasi-triple-peaked Br11 line profile is reported for HD253659, one of several stars exhibiting intra- and/or extra-species V/R and radial velocity variation within individual spectra. Br11 profiles are presented for all discussed stars, as are full APOGEE spectra for a portion of the sample.
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