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High-resolution, H band Spectroscopy of Be Stars with SDSS-III/APOGEE: I. New Be Stars, Line Identifications, and Line Profiles | | S. Drew Chojnowski
; David G. Whelan
; John P. Wisniewski
; Steven R. Majewski
; Matthew Hall
; Matthew Shetrone
; Rachael Beaton
; Adam Burton
; Guillermo Damke
; Steve Eikenberry
; Sten Hasselquist
; Jon A. Holtzman
; Szabolcs Meszaros
; David Nidever
; Donald P. Schneider
; John Wilson
; Gail Zasowski
; Dmitry Bizyaev
; Howard Brewington
; J. Brinkmann
; Garrett Ebelke
; Peter M. Frinchaboy
; Karen Kinemuchi
; Elena Malanushenko
; Viktor Malanushenko
; Moses Marchante
; Daniel Oravetz
; Kaike Pan
; Audrey Simmons
; | | Date: |
16 Sep 2014 | | Abstract: | APOGEE has amassed the largest ever collection of multi-epoch,
high-resolution (R~22,500), H-band spectra for B-type emission line (Be) stars.
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%. We focus
on identification of the H-band lines and analysis of the emission peak
velocity separations (v_p) and emission peak intensity ratios (V/R) of the
usually double-peaked H I and non-hydrogen emission lines. H I Br11 emission is
found to preferentially form in the circumstellar disks at an average distance
of ~2.2 stellar radii. Increasing v_p toward the weaker Br12--Br20 lines
suggests these lines are formed interior to Br11. By contrast, the observed IR
Fe II emission lines present evidence of having significantly larger formation
radii; distinctive phase lags between IR Fe II and H I 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
~16895, a prominent feature in the spectra for almost a fifth of the sample
and, as inferred from relatively large v_p compared to the Br11-Br20, a tracer
of the inner regions of Be disks. Unlike the typical metallic lines observed
for Be stars in the optical, the H-band metallic lines, such as Fe II 16878,
never exhibit any evidence of shell absorption, even when the H I lines are
clearly shell-dominated. The first known example of a quasi-triple-peaked Br11
line profile is reported for HD 253659, 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. | | Source: | arXiv, 1409.4668 | | Services: | Forum | Review | PDF | Favorites | |
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