J/AJ/149/153 Abundances of red giants in 10 globular clusters (Meszaros+, 2015)
Exploring anticorrelations and light element variations in northern globular
clusters observed by the APOGEE survey.
Meszaros S., Martell S.L., Shetrone M., Lucatello S., Troup N.W., Bovy J.,
Cunha K., Garcia-Hernandez D.A., Overbeek J.C., Allende Prieto C.,
Beers T.C., Frinchaboy P.M., Garcia Perez A.E., Hearty F.R., Holtzman J.,
Majewski S.R., Nidever D.L., Schiavon R.P., Schneider D.P., Sobeck J.S.,
Smith V.V., Zamora O., Zasowski G.
<Astron. J., 149, 153 (2015)>
=2015AJ....149..153M 2015AJ....149..153M
ADC_Keywords: Clusters, globular ; Stars, giant ; Abundances
Keywords: stars: abundances - stars: AGB and post-AGB -
stars: chemically peculiar - stars: evolution
Abstract:
We investigate the light-element behavior of red giant stars in
northern globular clusters (GCs) observed by the SDSS-III Apache Point
Observatory Galactic Evolution Experiment. We derive abundances of 9
elements (Fe, C, N, O, Mg, Al, Si, Ca, and Ti) for 428 red giant stars
in 10 GCs. The intrinsic abundance range relative to measurement
errors is examined, and the well-known C-N and Mg-Al anticorrelations
are explored using an extreme-deconvolution code for the first time in
a consistent way. We find that Mg and Al drive the population
membership in most clusters, except in M107 and M71, the two most
metal-rich clusters in our study, where the grouping is most sensitive
to N. We also find a diversity in the abundance distributions, with
some clusters exhibiting clear abundance bimodalities (for example M3
and M53) while others show extended distributions. The spread of Al
abundances increases significantly as cluster average metallicity
decreases as previously found by other works, which we take as
evidence that low metallicity, intermediate mass AGB polluters were
more common in the more metal-poor clusters. The statistically
significant correlation of [Al/Fe] with [Si/Fe] in M15 suggests that
28Si leakage has occurred in this cluster. We also present C, N, and
O abundances for stars cooler than 4500K and examine the behavior of
A(C+N+O) in each cluster as a function of temperature and [Al/Fe]. The
scatter of A(C+N+O) is close to its estimated uncertainty in all
clusters and independent of stellar temperature. A(C+N+O) exhibits
small correlations and anticorrelations with [Al/Fe] in M3 and M13,
but we cannot be certain about these relations given the size of our
abundance uncertainties. Star-to-star variations of α-element
(Si, Ca, Ti) abundances are comparable to our estimated errors in all
clusters.
Description:
We investigated the abundances of nine elements (Fe, C, N, O, Mg, Al,
Si, Ca, Ti) for 428 stars in 10 globular clusters (NGC 7078, NGC 6341,
NGC 5024, NGC 5466, NGC 6205, NGC 7089, NGC 5272, NGC 5904, NGC 6171,
and NGC 6838) using Apache Point Observatory Galactic Evolution
Experiment (APOGEE; Majewski et al. 2015, cat. J/AJ/149/7) DR10
spectra.
The APOGEE is a three-year, near-infrared (15090-16990Å),
high-resolution spectroscopic survey of about 100000 red giant stars
included as part of the third Sloan Digital Sky Survey (SDSS-III;
Eisenstein et al., 2011AJ....142...72E 2011AJ....142...72E). With a nominal resolving
power of 22500, APOGEE is deriving abundances of up to 15 elements for
nearly 100000 stars. APOGEE is in a unique position among the various
Galactic spectroscopic surveys, as it uses the Sloan 2.5m telescope at
Apache Point Observatory, and thereby has access to the northern
hemisphere. APOGEE observes a large sample of northern globular
clusters.
The spectra used in this paper are publicly available as part of the
10th data release (DR10; Ahn et al., 2014ApJS..211...17A 2014ApJS..211...17A) of SDSS-III.
The initial set of stars selected were the same used by Meszaros et
al. 2013 (cat. J/AJ/146/133) to check the accuracy and precision of
APOGEE parameters published in DR10. However, instead of using the
automatic APOGEE Stellar Parameters and Chemical Abundances Pipeline
(ASPCAP), we will make use of photometry and theoretical isochrones to
constrain the effective temperature (Teff) and surface gravity
log(g) and use an independent semi-automated method for elemental
abundance determination for 10 northern globular clusters.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 33 10 Properties of clusters from the literature
table2.dat 95 428 Properties of stars analyzed
table5.dat 114 289 Identifiers, stellar parameters, and elemental
abundances from the literature for stars in our sample
refs.dat 64 31 References
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
VII/202 : Globular Clusters in the Milky Way (Harris, 1997)
J/AJ/149/7 : SDSS-III/APOGEE. I. Be stars (Chojnowski+, 2015)
J/AJ/148/24 : Extinction maps in the bulge from APOGEE (Schultheis+, 2014)
J/AJ/146/156 : APOGEE M-dwarf survey. I. (Deshpande+, 2013)
J/AJ/146/133 : Stellar parameters from SDSS-III APOGEE DR10 (Meszaros+, 2013)
J/ApJ/754/L38 : Abundances & radial velocities of M13 giants (Johnson+, 2012)
J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)
J/AJ/141/62 : M5 chemical abundances for evolved stars (Lai+, 2011)
J/AJ/140/1119 : Radial velocities of NGC 5466 members (Shetrone+, 2010)
J/AJ/139/2289 : Abundances of five red giants in M5 (Koch+, 2010)
J/A+A/505/139 : Abundances of red giants in 17 GCs (Carretta+, 2009)
J/A+A/505/117 : Abundances of red giants in 15 GCs (Carretta+, 2009)
J/ApJ/689/1031 : Heavy element abundances in giant stars (Yong+, 2008)
J/A+A/464/967 : Abundances of red giants in NGC 6388 (Carretta+, 2007)
J/ApJ/638/1018 : Equivalent widths for giant stars in M13 and M71 (Yong+, 2006)
J/AJ/129/303 : Abundances of stars in M3 and M13 (Cohen+, 2005)
J/AJ/120/1364 : Abundances in M3 and M13 (Cavallo+, 2000)
http://sdss3.org/ : SDSS-III website
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [NGC]
5- 8 I4 --- NGC NGC number of the cluster
10- 14 A5 --- Cluster Cluster name
15- 17 I3 --- Nst [8/122] Number of stars observed in cluster
19- 23 F5.2 [Sun] [Fe/H] Log Fe/H number abundance (1)
25- 28 F4.2 [Sun] e_[Fe/H] Uncertainty in [Fe/H]
30- 33 F4.2 mag E(B-V) The (B-V) color excess (2)
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Note (1): From Harris 1996 (cat. VII/195, cat. VII/202) 2010 edition. Clusters
are listed in order of the average cluster metallicity determined in this
paper.
Note (2): From Harris 1996 (cat. VII/195, cat. VII/202) 2010 edition.
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- --- [2M]
3- 18 A16 --- 2MASS Star 2MASS identifier (HHMMSSss+DDMMSSs, J2000)
20- 24 A5 --- Cluster Cluster name
26- 31 F6.1 km/s HV Heliocentric velocity
33- 36 I4 K Teff Photometric effective temperature
38- 41 F4.2 [cm/s2] logg [0.3/4] Log surface gravity; from isochrones
43- 47 F5.2 [Sun] [Fe/H] [-2.6/-0.6] Log Fe/H abundance
49- 53 F5.2 [Sun] [C/Fe] ? Log C/Fe abundance
55- 59 F5.2 [Sun] [N/Fe] ? Log N/Fe abundance
61- 65 F5.2 [Sun] [O/Fe] ? Log O/Fe abundance
67- 71 F5.2 [Sun] [Mg/Fe] ? Log Mg/Fe abundance
73- 77 F5.2 [Sun] [Al/Fe] ? Log Al/Fe abundance
79- 83 F5.2 [Sun] [Si/Fe] ? Log Si/Fe abundance
85- 89 F5.2 [Sun] [Ca/Fe] ? Log Ca/Fe abundance
91- 95 F5.2 [Sun] [Ti/Fe] ? Log Ti/Fe abundance
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- --- [2M]
3- 18 A16 --- 2MASS Star 2MASS identifier (HHMMSSss+DDMMSSs, J2000)
20- 23 A4 --- Cluster Cluster name
25- 28 I4 K Teff ? Effective temperature
30- 33 F4.2 [cm/s2] logg ? Log surface gravity
35- 40 F6.3 [Sun] [Fe/H] ? Log Fe/H abundance
42- 46 F5.2 [Sun] [C/Fe] ? Log C/Fe abundance
48- 52 F5.2 [Sun] [N/Fe] ? Log N/Fe abundance
54- 59 F6.3 [Sun] [O/Fe] ? Log O/Fe abundance
61- 66 F6.3 [Sun] [Mg/Fe] ? Log Mg/Fe abundance
68 A1 --- l_[Al/Fe] [<] Upper limit flag on [Al/Fe]
69- 74 F6.3 [Sun] [Al/Fe] ? Log Al/Fe abundance
76- 80 F5.3 [Sun] [Si/Fe] ? Log Si/Fe abundance
82- 86 F5.2 [Sun] [Ca/Fe] ? Log Ca/Fe abundance
88- 91 F4.2 [Sun] [Ti/Fe] ? Log Ti/Fe abundance
93-111 A19 --- OName Other name(s)
113-114 A2 --- Ref Literature reference code; in refs.dat file
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- Ref Reference identifier
4- 22 A19 --- BibCode Bibliographic code
24- 44 A21 --- Aut Author's name
46- 64 A19 --- Cat Catalog in the VizieR database
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 22-May-2015