J/ApJ/829/116 H-band spectroscopic analysis of 25 bright M31 GCs (Sakari+, 2016)
Infrared high-resolution integrated light spectral analyses of
M31 globular clusters from APOGEE.
Sakari C.M., Shetrone M.D., Schiavon R.P., Bizyaev D., Prieto C.A.,
Beers T.C., Caldwell N., Garcia-Hernandez D.A., Lucatello S., Majewski S.,
O'Connell R.W., Pan K., Strader J.
<Astrophys. J., 829, 116-116 (2016)>
=2016ApJ...829..116S 2016ApJ...829..116S (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Abundances ; Spectra, infrared ;
Galaxies, nearby ; Spectroscopy
Keywords: galaxies: abundances; galaxies: evolution; galaxies: individual: M31;
galaxies: star clusters: general; globular clusters: general
Abstract:
Chemical abundances are presented for 25 M31 globular clusters (GCs),
based on moderately high resolution (R=22500) H-band integrated light
(IL) spectra from the Apache Point Observatory Galactic Evolution
Experiment (APOGEE). Infrared (IR) spectra offer lines from new
elements, lines of different strengths, and lines at higher excitation
potentials compared to the optical. Integrated abundances of C, N, and
O are derived from CO, CN, and OH molecular features, while Fe, Na,
Mg, Al, Si, K, Ca, and Ti abundances are derived from atomic features.
These abundances are compared to previous results from the optical,
demonstrating the validity and value of IR IL analyses. The CNO
abundances are consistent with typical tip of the red giant branch
stellar abundances but are systematically offset from optical Lick
index abundances. With a few exceptions, the other abundances agree
between the optical and the IR within the 1σ uncertainties. The
first integrated K abundances are also presented and demonstrate that
K tracks the α elements. The combination of IR and optical
abundances allows better determinations of GC properties and enables
probes of the multiple populations in extragalactic GCs. In
particular, the integrated effects of the Na/O anticorrelation can be
directly examined for the first time.
Description:
H-band spectra (1.51-1.69um) of the target clusters were obtained with
the moderately high resolution (R=22500) APOGEE spectrograph on the
2.5m Telescope at Apache Point Observatory in 2011 and 2013. The
details of the observations can be found in Majewski+
(2015arXiv150905420M 2015arXiv150905420M) and Zasowski+ (2013AJ....146...81Z 2013AJ....146...81Z), including
descriptions of the plates and fibers that were utilized for the
observations.
The high-resolution optical abundances from Colucci et al. (2009,
J/ApJ/704/385 and 2014ApJ...797..116C 2014ApJ...797..116C) are supplemented with new
results for five globular clusters (GCs).
The new optical spectra were obtained in 2009 and 2010 with the High
Resolution Spectrograph on the Hobby-Eberly Telescope at McDonald
Observatory in Fort Davis, TX (R=30000; spectral coverage over
∼5320-6290 and ∼6360-7340Å in the blue and the red, respectively).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 80 25 Target list
table2.dat 55 25 Mean H-band abundances and random errors: Fe, C,
N, and O
table3.dat 79 25 Mean H-band abundances and random errors: Na, Mg,
Al, Si, Ca, and Ti
table7.dat 85 5 Observation information and derived isochrones
for new optical data
table8.dat 57 134 Line list for optical abundances
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See also:
V/143 : Revised Bologna Catalog of M31 clusters, V.5 (Galleti+ 2012)
J/AJ/151/144 : ASPCAP weights of 15 APOGEE chemical elements (Garcia+, 2016)
J/ApJS/221/24 : SDSS-III APOGEE H-band spectral line lists (Shetrone+, 2015)
J/ApJ/813/97 : M62 (NGC 6266) giant branch stars abundances (Lapenna+, 2015)
J/AJ/149/153 : Abundances of red giants in 10 GCs (Meszaros+, 2015)
J/MNRAS/434/358 : 4 Galactic globular clusters Fe line depths (Sakari+, 2013)
J/ApJ/773/L36 : NGC 5128 globular cluster abundances (Colucci+, 2013)
J/ApJ/746/29 : High-resolution GC abundances. IV. 8 LMC GCs (Colucci+, 2012)
J/AJ/143/14 : Lick indices of M31 globular clusters (Schiavon+, 2012)
J/AJ/141/61 : Star clusters in M31. II. (Caldwell+, 2011)
J/A+A/508/1285 : Metallicity estimates of M31 GCs (Galleti+, 2009)
J/A+A/507/1375 : HST/ACS VI data of M31 globular clusters (Perina+, 2009)
J/ApJ/704/385 : M31 integrated light abundances (Colucci+, 2009)
J/A+A/505/139 : Abundances of red giants in 17 GCs (Carretta+, 2009)
J/AJ/137/94 : Star clusters in M31 (Caldwell+, 2009)
J/AJ/133/2764 : M31 globular clusters structural parameters (Barmby+, 2007)
J/AJ/123/2490 : RV and [Fe/H] of M31 globular cluster system (Perrett+, 2002)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- Bol Cluster name
5 A1 --- --- [-]
6- 9 A4 --- SKHB Other cluster name
11- 13 A3 --- f_Bol Flag(s) on Bol (1)
15- 16 I2 h RAh Hour of right ascension (J2000) (2)
18- 19 I2 min RAm Arcminute of right ascension (J2000)
21- 24 F4.1 s RAs Arcsecond of right ascension (J2000)
26 A1 --- DE- Sign of declination (J2000) (2)
27- 28 I2 deg DEd Degree of declination (J2000) (2)
30- 31 I2 arcmin DEm Arcminute of declination (J2000)
33- 36 F4.1 arcsec DEs Arcsecond of declination (J2000)
38- 42 F5.2 kpc Rproj [1.7/18.3] Pojected distance from the
center of M31 (2)
44- 48 F5.2 mag Vmag [14/16.6] V-band magnitude (2)
50- 54 F5.2 mag Hmag [11.2/13.5] H-band magnitude (2)
56- 60 A5 --- Epoch Observing epoch(s) (Clusters were observed in
2011 and/or 2013)
62- 63 I2 --- Nv [3/11] Number of visits (3)
65- 69 F5.2 --- S/N [7.9/65.8] Signal-to-noise ratio (4)
71- 76 F6.1 km/s HRV [-555/-54] Heliocentric velocity
78- 80 F3.1 km/s e_HRV [0.3/1] HRV uncertainty
--------------------------------------------------------------------------------
Note (1): Flag as follows:
d = Some visits were affected by superpersistence (see text). The
superpersistence regions are masked out, leading to lower S/N in the
1.51-1.62um region; some abundances are derived with unmasked spectra and
have been flagged in subsequent tables.
e = All visits were affected by superpersistence. Spectral range of this
cluster is limited due to superpersistence; see Section 2.2.
f = A background galactic component was subtracted during data reduction.
Note (2): Positions, projected distances from the center of M31, and magnitudes
are from the Revised Bologna Catalog (Galleti+ 2012, V/143).
Note (3): Each visit is 66.6min of integration.
Note (4): Signal-to-noise ratios (S/Ns) are per pixel and represent the median
value across the entire spectral range. There are approximately
2.06 pixels per resolution element in the blue, 2.27 in the green, and
2.66 in the red.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Bol Globular cluster ID
6- 10 F5.2 --- [FeI/H] [-1.9/-0.1] The H-band FeI abundance
12- 15 F4.2 --- e_[FeI/H] [0.03/0.2] [FeI/H] uncertainty
17- 18 I2 --- NFeI [2/13] Number of measured lines for [FeI/H]
20- 24 F5.2 --- [C/Fe] [-0.6/-0.03] [C/Fe] abundance (5)
26- 29 F4.2 --- e_[C/Fe] [0.04/0.2] [C/Fe] uncertainty
31 I1 --- NC [1/5] Number of measured lines for [C/Fe]
33- 36 F4.2 --- [N/Fe] [0.9/1.4] [N/Fe] abundance (5)
38- 41 F4.2 --- e_[N/Fe] [0.04/0.2] [N/Fe] uncertainty
43 I1 --- NN [1/8] Number of measured lines for [N/Fe]
45- 48 F4.2 --- [O/Fe] [0.07/0.6] [O/Fe] abundance (5)
50- 53 F4.2 --- e_[O/Fe] [0.03/0.8] [O/Fe] uncertainty
55 I1 --- NO [1/5] Number of measured lines for [O/Fe]
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Note (5): CNO abundances are determined from the CO, CN, and OH molecular lines
in Smith et al. (2013ApJ...765...16S 2013ApJ...765...16S), assuming 12C/13C=6
(see the text).
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- Bol Globular cluster name
6- 9 F4.2 --- [Na/Fe] [0.3/0.7]? H-band Na abundance
11- 14 F4.2 --- e_[Na/Fe] [0.05/0.2]? [Na/Fe] uncertainty
16 I1 --- NNa [1/2]? Number of measured lines for [Na/Fe]
18- 22 F5.2 --- [Mg/Fe] [-0.2/0.5]? H-band Mg abundance
24- 27 F4.2 --- e_[Mg/Fe] [0.05/0.2]? [Mg/Fe] uncertainty
29 I1 --- NMg [1/4]? Number of measured lines for [Mg/Fe]
31- 34 F4.2 --- [Al/Fe] [0.1/0.7]? H-band Al abundance
36- 39 F4.2 --- e_[Al/Fe] [0.05/0.2]? [Al/Fe] uncertainty
41 I1 --- NAl [1/2]? Number of measured lines for [Al/Fe]
43 A1 --- f_NAl [a] Flag on NAl (6)
45- 48 F4.2 --- [Si/Fe] [0.1/0.6] H-band [Si/Fe] abundance
50- 53 F4.2 --- e_[Si/Fe] [0.05/0.2] [Si/Fe] uncertainty
55 I1 --- NSi [1/5] Number of measured lines for [Si/Fe]
57- 60 F4.2 --- [Ca/Fe] [0.2/0.5]? H-band [Ca/Fe] abundance
62- 65 F4.2 --- e_[Ca/Fe] [0.05/0.4]? [Ca/Fe] uncertainty
67 I1 --- NCa [1/4]? Number of measured lines for [Ca/Fe]
69- 72 F4.2 --- [Ti/Fe] [0.2/0.5]? H-band [Ti/Fe] abundance
74- 77 F4.2 --- e_[Ti/Fe] [0.07/0.2]? [Ti/Fe] uncertainty
79 I1 --- NTi [1/3]? Number of measured lines for [Ti/Fe]
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Note (6):
a = This H-band abundance was derived from at least one strong line with
-4.7<REW -4.5, which may lead to systematic uncertainties of ∼0.1dex
(McWilliam+ 1995AJ....109.2757M 1995AJ....109.2757M).
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- Bol Globular cluster ID
6- 45 A40 --- Date UT dates of observation
47- 51 I5 s Texp [10565/16200] Exposure time
53- 55 I3 --- S/N [120/250] 6000Å signal-to-noise ratio (1)
57- 62 F6.1 km/s HRV [-516/-120] Heliocentric radial velocity
64- 66 F3.1 km/s e_HRV [0.5/1] HRV uncertainty
68- 72 F5.2 km/s sigma [10.5/17] Velocity dispersion
74- 76 F3.1 km/s e_sigma [0.4/0.6] sigma uncertainty
78- 82 F5.2 --- [Fe/H] [-1.7/-0.6] Isochrone metallicity
84- 85 I2 Gyr Age [11/14] Age
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Note (1): S/N is per resolution element; there are 2.7 pixels per resolution
element.
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.3 0.1nm lambda [5324/7326.2] Spectral line wavelength; Angstroms
10- 13 A4 --- El Element and ionization state
16- 20 F5.3 eV EP [0/6] Excitation Potential
22- 27 F6.3 --- loggf [-5.8/0.7] Log oscillator strength
29- 33 F5.1 10-13m B006EW [21/120]? B006 Equivalent width; milliAngstroms
35- 39 F5.1 10-13m B063EW [15/114.1]? B063 Equivalent width; mÅ
41- 45 F5.1 10-13m B171EW [26/143]? B171 Equivalent width; milliAngstroms
47- 51 F5.1 10-13m B311EW [13/149]? B311 Equivalent width; milliAngstroms
53- 57 F5.1 10-13m B472EW [11/118]? B472 Equivalent width; milliAngstroms
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 15-Dec-2016