J/ApJ/859/75 NGC 5824 giant star members from VLT obs. (Mucciarelli+, 2018)
The chemical composition of NGC 5824, a globular cluster without iron spread
but with an extreme Mg-Al anticorrelation.
Mucciarelli A., Lapenna E., Ferraro F.R., Lanzoni B.
<Astrophys. J., 859, 75 (2018)>
=2018ApJ...859...75M 2018ApJ...859...75M
ADC_Keywords: Clusters, globular; Stars, giant; Abundances; Radial velocities;
Photometry, UBV; Spectra, infrared
Keywords: globular clusters: individual (NGC 5824) ; stars: abundances ;
techniques: spectroscopic
Abstract:
NGC 5824 is a massive Galactic globular cluster suspected to have an
intrinsic spread in its iron content, according to the strength of the
calcium triplet lines. We present chemical abundances of 117 cluster
giant stars using high-resolution spectra acquired with the
multi-object spectrograph FLAMES. The metallicity distribution of 87
red giant branch stars is peaked at [Fe/H]=-2.11±0.01dex, while that
derived from 30 asymptotic giant branch stars is peaked at
[Fe/H]=-2.20±0.01dex. Both the distributions are compatible with a
null spread, indicating that this cluster did not retain the ejecta of
supernovae. The small iron abundance offset between the two groups of
stars is similar to the abundances already observed among red and
asymptotic giant branch stars in other clusters. The lack of intrinsic
iron spread rules out the possibility that NGC 5824 is the remnant of
a disrupted dwarf galaxy, as previously suggested. We also find
evidence of the chemical anomalies usually observed in globular
clusters, namely the Na-O and the Mg-Al anticorrelations. In
particular, NGC 5824 exhibits a huge range of [Mg/Fe] abundance,
observed in only a few metal-poor and/or massive clusters. We conclude
that NGC 5824 is a normal globular cluster, without spread in [Fe/H]
but with an unusually large spread in [Mg/Fe], possibly due to an
efficient self-enrichment driven by massive asymptotic giant branch
stars.
Description:
The observations have been collected under the program 095.D-0290 (PI:
Mucciarelli) and performed during the night of 2015 May 28 with the
multi-object spectrograph FLAMES at the Very Large Telescope (VLT) of
ESO in the GIRAFFE+UVES combined mode.
The adopted setups are GIRAFFE HR21 (with a spectral coverage of
∼8480-9000Å and a spectral resolution of 18000) and UVES Red Arm
580 (with a spectral coverage of ∼4800-6800Å and a spectral
resolution of 45000).
We identified likely cluster member stars according to their RV and
[Fe/H]. A total of 117 cluster member stars are identified (for the
GIRAFFE targets). See section 6.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 68 117 Main information on the spectroscopic targets
of NGC 5824
table2.dat 35 191 Wavelength, species, oscillator strength,
excitation potential of the used transitions
table3.dat 97 6 Atmospheric parameters and abundance ratios for
the UVES targets of NGC 5824
table4.dat 52 117 Atmospheric parameters and abundance ratios for
the GIRAFFE target members of NGC 5824
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See also:
VII/202 : Globular Clusters in the Milky Way (Harris, 1997)
J/AJ/118/1245 : Elemental abundances in five stars in M54 (Brown+, 1999)
J/AJ/128/1177 : Galactic stellar abundances (Venn+, 2004)
J/A+A/505/117 : Abundances of red giants in 15 GCls (Carretta+, 2009)
J/A+A/505/139 : Abundances of red giants in 17 GCls (Carretta+, 2009)
J/ApJ/705/328 : Abundance measurements in Sculptor dSph (Kirby+, 2009)
J/A+A/520/A95 : Abundances of red giants in M54 & Sgr dSph (Carretta+, 2010)
J/ApJ/722/1373 : ω Centauri giants abundances (Johnson+, 2010)
J/ApJ/738/186 : HST and DEIMOS measurements of NGC 2419 stars (Ibata+, 2011)
J/ApJ/731/64 : Spectroscopy of 300 RGBs in ω Cen (Marino+, 2011)
J/ApJ/726/L20 : Spectroscopy of Terzan 5 (Origlia+, 2011)
J/A+A/527/A18 : EW of 6 subgiants of ω Cen (Pancino+, 2011)
J/ApJ/760/86 : Equivalent widths for 13 NGC2419 RGB stars (Cohen+, 2012)
J/A+A/540/A27 : Spectroscopy in Galactic globular clusters (Saviane+, 2012)
J/A+A/561/A87 : FLAMES observations of Terzan 8 (Carretta+, 2014)
J/MNRAS/438/3507 : NGC 5824 calcium triplet equivalent widths (Da Costa+, 2014)
J/ApJ/797/124 : AGB and RGB stars in 47 Tuc (Lapenna+, 2014)
J/ApJ/795/22 : Iron abundance of Terzan 5 stars (Massari+, 2014)
J/ApJ/813/97 : M62 (NGC 6266) giant branch star abundances (Lapenna+, 2015)
J/MNRAS/450/815 : Red giants in NGC 5286 (Marino+, 2015)
J/AJ/149/153 : Abundances of red giants in 10 GCls (Meszaros+, 2015)
J/ApJ/801/69 : Iron EWs for 21 giant stars of NGC3201 (Mucciarelli+, 2015)
J/AJ/152/21 : Red giant abundances in NGC6342 & NGC6366 (Johnson+, 2016)
J/A+A/605/A46 : Sgr dSph nucleus stars abundances (Mucciarelli+, 2017)
J/A+A/603/L7 : 6 giants atomic data and EWs (Mucciarelli+, 2017)
J/A+A/601/A112 : GES iDR4 Mg-Al anticorrelation in GCs (Pancino+, 2017)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- S14 [8953/41744] Identifier from
Sanna+ 2014ApJ...780...90S 2014ApJ...780...90S
7- 14 I8 --- [DHS2014] [11001198/71002877]?=0 Identifier from
Da Costa+ 2014, J/MNRAS/438/3507
16- 26 F11.7 deg RAdeg [225.9/226.2] Right Ascension (J2000)
28- 38 F11.7 deg DEdeg [-33.2/-32.9] Declination (J2000)
40- 45 F6.3 mag Umag [17.8/19.1] Apparent Johnson U band magnitude
47- 52 F6.3 mag Vmag [15.5/18] Apparent Johnson V band magnitude
54- 59 F6.2 km/s HRV [-42.6/-9.5] Heliocentric radial velocity
61- 64 F4.2 km/s e_HRV [0.01/0.5] Uncertainty in HRV
66- 68 A3 --- Evol Evolutionary sequence ("RGB"=87 occurrences; or
"AGB")
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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- 8 F8.3 0.1nm lambda [4859.7/8868.5] Wavelength in Angstroms
10- 14 A5 --- Sp Species identifier
16- 21 F6.3 [-] log(gf) [-6.125/0.645] log oscillator strength
23- 27 F5.3 eV ExPot [0.052/4.991] Excitation potential
29- 35 A7 --- Inst Instrument use in measurement
("UVES"=174 occurrences or "GIRAFFE")
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- S14 [20836/35432] Sanna+ 2014ApJ...780...90S 2014ApJ...780...90S
identifier
7- 10 I4 K Teff [4238/4344] Effective temperature
12- 15 F4.2 [cm/s2] logg [0.6/0.9] log surface gravity
17- 19 F3.1 km/s Vt [1.9/2] Turbulent velocity
21- 25 F5.2 [Sun] [Fe/H] [-2.2/-2] Metallicity
27- 30 F4.2 [Sun] e_[Fe/H] [0.06] Uncertainty in [Fe/H]
32- 36 F5.2 [Sun] [O/Fe] [-2.1/-1.9] log O/Fe abundance ratio
38- 41 F4.2 [Sun] e_[O/Fe] [0.08/0.09] Uncertainty in [O/Fe]
43- 46 F4.2 [Sun] [Na/Fe] [0.08/0.09] log Na/Fe abundance ratio
48- 51 F4.2 [Sun] e_[Na/Fe] [0.03/0.08] Uncertainty in [Na/Fe]
53- 57 F5.2 [Sun] [Mg/Fe] [-0.3/0.5] log Mg/Fe abundance ratio
59- 62 F4.2 [Sun] e_[Mg/Fe] [0.02/0.08] Uncertainty in [Mg/Fe]
64 A1 --- l_[Al/Fe] Limit flag on [Al/Fe]
65- 68 F4.2 [Sun] [Al/Fe] [0.2/1.3] log Al/Fe abundance ratio
70- 73 F4.2 [Sun] e_[Al/Fe] [0.03]? Uncertainty in [Al/Fe]
75- 85 F11.7 deg RAdeg Right ascension (J2000) (1)
87- 97 F11.7 deg DEdeg Declination (J2000) (1)
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Note (1): Coordinates sent by the author.
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- S14 [8953/41744] Sanna+ 2014ApJ...780...90S 2014ApJ...780...90S
identifier
7- 10 I4 K Teff [4097/5107] Effective temperature
12- 14 F3.1 [cm/s2] logg [0.5/1.9] log surface gravity
16- 18 F3.1 km/s Vt [1.7/2.1] Turbulent velocity
20- 24 F5.2 [Sun] [Fe/H] [-2.3/-1.9] Metallicity
26- 29 F4.2 [Sun] e_[Fe/H] [0.05/0.09] Uncertainty in [Fe/H]
31- 35 F5.2 [Sun] [Mg/Fe] [-0.4/0.8] log Mg/Fe abundance ratio
37- 40 F4.2 [Sun] e_[Mg/Fe] [0.02/0.2] Uncertainty in [Mg/Fe]
42 A1 --- l_[Al/Fe] Lower limit flag on [Al/Fe]
43- 47 F5.2 [Sun] [Al/Fe] [-0.2/1.4] log Al/Fe abundance ratio
49- 52 F4.2 [Sun] e_[Al/Fe] [0.03/0.2]? Uncertainty in [Alg/Fe]
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Acknowledgements:
Alessio Mucciarelli, University of Bologna - www.cosmic-lab.eu/
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 29-May-2019