J/AJ/149/7 SDSS-III/APOGEE. I. Be stars (Chojnowski+, 2015)
High-resolution H-band spectroscopy of Be stars with SDSS-III/APOGEE:
I. New Be stars, line identifications, and line profiles.
Chojnowski S.D., Whelan D.G., Wisniewski J.P., Majewski S.R., Hall M.,
Shetrone M., Beaton R., Burton A., Damke G., Eikenberry S., Hasselquist S.,
Holtzman J.A., Meszaros S., Nidever D., Schneider D.P., Wilson J.,
Zasowski G., Bizyaev D., Brewington H., Brinkmann J., Ebelke G.,
Frinchaboy P.M., Kinemuchi K., Malanushenko E., Malanushenko V.,
Marchante M., Oravetz D., Pan K., Simmons A.
<Astron. J., 149, 7 (2015)>
=2015AJ....149....7C 2015AJ....149....7C
ADC_Keywords: Stars, Be ; Stars, emission ; Spectroscopy ; Spectral types
Keywords: circumstellar matter - infrared: stars - line: identification -
line: profiles - stars: early-type - stars: emission-line, Be
Abstract:
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
(Δvp) 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 Δvp
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
Δvp compared to the Br11-Br20, a tracer of the inner
regions of Be disks. Emission lines at 15760Å and 16781Å 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.
Description:
The sample at hand consists of 238 B-type emission line (Be) stars
that have been observed by APOGEE.
The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
instrument is a 300 fiber, R∼22500 spectrograph attached to the SDSS
2.5m telescope at Apache Point Observatory. APOGEE records a vacuum
wavelength range of 15145-16955Å via an arrangement of three
Teledyne H2RG 2048*2048 detectors. The detector layout consists of
"blue," "green," and "red" detectors which cover 15145-15808Å,
15858-16433Å, and 16474-16955Å respectively, resulting in
coverage gaps between 15808-15858Å and 16433-16474Å.
The APOGEE survey uses the Two Micron All Sky Survey (2MASS; cat. II/246)
as a source catalog.
Both proprietary and publicly available spectra are used and displayed
in this paper. The publicly available spectra were included in SDSS
data release 10 (DR10: pertains to APOGEE data taken prior to
MJD=56112), and the full data set will be made publicly available in
SDSS data release 12 (DR12: scheduled for 2014 December). Shortly
after DR12, we intend to convert the ABE star spectra to the format
accepted by the Be Star Spectra Database (BeSS; Neiner et al.,
2011AJ....142..149N 2011AJ....142..149N) and deposit them there, ensuring convenient
public access. More details on DR10-released APOGEE data can be found
on the SDSS-III website (http://www.sdss3.org/dr10/irspec/).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 130 261 List of ABE (APOGEE Be) stars
refs.dat 70 77 References
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See also:
B/mk : Catalogue of Stellar Spectral Classifications (Skiff, 2009-2014)
http://www.sdss3.org/dr10/irspec/ : SDSS-III website
J/AJ/148/24 : Extinction maps in the bulge from APOGEE (Schultheis+, 2014)
J/AJ/146/156 : APOGEE M-dwarf survey. I. 1st yr velocities (Deshpande+, 2013)
J/AJ/146/133 : Stellar parameters from SDSS-III APOGEE DR10 (Meszaros+, 2013)
J/other/BASI/39.517 : Spectroscopy of classical Be stars (Mathew+, 2011)
J/ApJ/700/1216 : Spectroscopy of Be stars in open clusters (McSwain+, 2009)
J/A+A/459/137 : Bright Be shell stars (Rivnius+, 2006)
J/A+A/451/1053 : Fundamental parameters of Be stars (Fremat+, 2006)
J/A+A/378/861 : Spectroscopy of Be stars (Chauville+, 2001)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- n_ABE [TAQ] Group of ABE stars (1)
3- 5 A3 --- ABE Identifier of the APOGEE B-type emission
line (Be) star (2)
7- 9 A3 --- New Indicates a newly identified Be star
11- 26 A16 --- 2MASS 2MASS identifier (Cat. II/246)
28- 33 I6 --- HD ? HD identifier
35- 50 A16 --- Name Common star name
52- 56 F5.2 mag Vmag V band magnitude from SIMBAD database
58- 63 F6.3 mag Hmag 2MASS H band magnitude
65- 75 A11 --- SpT Literature spectral type
77- 80 A4 --- f_SpT Indicates that the original source of the
spectral type could not be tracked down (3)
82- 83 I2 --- r_SpT ? Reference on SpT where available;
in refs.dat file
85 A1 --- l_dVBr11 [<] Upper limit flag on dVBr11
86- 89 I4 km/s dVBr11 ? Mean velocity separation of the violet and
red emission peaks Δvp of
Br11 1.6811µm
91- 96 A6 --- f_dVBr11 No velocity despite line detection (4)
98-100 I3 km/s dV15760 ? Δvp of 1.5760µm emission
102-103 A2 --- f_dV15760 No velocity despite line detection (4)
105-107 I3 km/s dV16781 ? Δvp of 1.6781µm emission
109-110 A2 --- f_dV16781 No velocity despite line detection (4)
112-113 I2 km/s dV16792 ? Δvp of FeII 1.6792µm emission
115-116 A2 --- f_dV16792 No velocity despite line detection (4)
118-120 I3 km/s dV16878 ? Δvp of FeII 1.6878µm emission
122-123 A2 --- f_dV16878 No velocity despite line detection (4)
125-127 I3 km/s dVCI ? Δvp of CI 1.6895µm emission
129-130 A2 --- f_dVCI No velocity despite line detection (4)
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Note (1): The APOGEE B-type emission line (ABE) identifiers were assigned to
avoid the use of sometimes lengthy survey identifiers which are the only
star names available. Three groups of ABE stars are distinguished from one
another by ABE identifier as follows:
T = Be stars that were quasi-randomly targeted by the Apache Point
Observatory Galactic Evolution Experiment (APOGEE) as telluric standard
stars (TSS) and subsequently identified as Be stars through visual
inspection of the wavelength region encompassing Br11 and FeII 16878.
To account for sources only producing emission lines in certain epochs,
which was frequently the case, it was necessary to examine all >70000
individual spectra for all >17000 telluric stars;
A = Be stars that we targeted intentionally via internal proposals for
APOGEE observations of ancillary (hence the "A" prefix of the ABE IDs)
science targets falling within a subset of pre-planned APOGEE fields.
Most of the intentionally targeted Be stars are early-type (B3 and
hotter) classical Be stars, showing stronger than average H-band
emission in the APOGEE spectra, but two stars classified as B[e] in the
literature were observed (ABE-A23 and ABE-A35) as was a reported Herbig
Ae star (ABE-A33);
Q = Stars which (a) had existing "emission line star" classifications in
the literature, (b) appeared to be hot OBA stars in the APOGEE spectra,
but (c) did not produce any discernible emission in any of the
associated APOGEE data (all have multi-epoch data), or in others words,
were H-band quiescent (hence the "Q" of the ABE IDs) during the
observations.
Note (2): APOGEE is the Apache Point Observatory Galactic Evolution Experiment
(APOGEE; Majewski, 2012AAS...21920506M 2012AAS...21920506M).
Note (3): The flag on spectral type is defined as follows:
CSSC = The Catalogue of Stellar Spectral Classification (CSSC; Skiff 2013,
cat. B/mk) was the primary resource used for locating spectral type
information, but some of the original sources of spectral types in the
CSSC (primarily those pre-dating 1940) could not be tracked down (in
those cases, the spectral types are enclosed in parentheses). Other
second-hand spectral types, culled from modern compilations of
historical data, are also enclosed in parentheses.
Note (4): Mean emission peak velocity separation Δvp measurement
could not be made in any of the available spectra despite evidence of
emission or shell absorption. In place of a Δvp value, an
abbreviation is provided as follows:
w = Weak emission-peaks not discernible;
w? = Weak or ambiguous detection;
sp = Single-peaked emission;
sh = Shell absorption without resolved adjacent emission peaks;
as = Highly asymmetric emission peaks such that only one is visible
(not the same as single-peaked; ABE-056 and ABE- A03);
bl = V peak of Br11 is severely blended with FeII 16792 (ABE-013);
tc = Spectra are heavily contaminated by telluric features (ABE-058).
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ref Reference identifier
4- 22 A19 --- BibCode Bibliographic code
24- 45 A22 --- Aut Author's name
47- 70 A24 --- Cat Catalog in VizieR database
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History:
From electronic version of the journal
References:
Chojnowski et al., Paper II. 2017AJ....153..174C 2017AJ....153..174C, Cat. J/AJ/153/174
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 29-Jan-2015