J/AJ/155/71 RGB & HB members of the bulge cluster NGC 6569 (Johnson+, 2018)
Exploring the chemical composition and double horizontal branch of the bulge
globular cluster NGC 6569.
Johnson C.I., Rich R.M., Caldwell N., Mateo M., Bailey J.I., Olszewski E.W.,
Walker M.G.
<Astron. J., 155, 71 (2018)>
=2018AJ....155...71J 2018AJ....155...71J (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Clusters, globular ; Stars, giant ;
Stars, horizontal branch ; Photometry, infrared ;
Radial velocities ; Abundances ; Equivalent widths
Keywords: globular clusters: general -
globular clusters: individual (NGC 6569) - stars: abundances
Abstract:
Photometric and spectroscopic analyses have shown that the Galactic bulge
cluster Terzan 5 hosts several populations with different metallicities
and ages that manifest as a double red horizontal branch (HB). A recent
investigation of the massive bulge cluster NGC 6569 revealed a similar,
though less extended, HB luminosity split, but little is known about
the cluster's detailed chemical composition. Therefore, we have used
high-resolution spectra from the Magellan-M2FS and VLT-FLAMES
spectrographs to investigate the chemical compositions and radial velocity
distributions of red giant branch and HB stars in NGC 6569. We found
the cluster to have a mean heliocentric radial velocity of -48.8 km/s
(σ=5.3 km/s; 148 stars) and <[Fe/H]≥-0.87 dex (19 stars), but the
cluster's 0.05 dex [Fe/H] dispersion precludes a significant metallicity
spread. NGC 6569 exhibits light- and heavy-element distributions that
are common among old bulge/inner Galaxy globular clusters, including
clear (anti)correlations between [O/Fe], [Na/Fe], and [Al/Fe]. The
light-element data suggest that NGC 6569 may be composed of at least
two distinct populations, and the cluster's low <[La/Eu]≥-0.11 dex
indicates significant pollution with r-process material. We confirm
that both HBs contain cluster members, but metallicity and light-element
variations are largely ruled out as sources for the luminosity difference.
However, He mass fraction differences as small as ΔY∼0.02
cannot be ruled out and may be sufficient to reproduce the double HB.
Description:
The primary data obtained for this project were acquired on 2014 June 03
for the RGB sample and between 2016 June 28 and July 01 for the HB sample.
All observations utilized the Magellan-Clay 6.5 m telescope at Las
Campanas Observatory instrumented with the Michigan-Magellan Fiber
System (M2FS; Mateo et al. 2012SPIE.8446E..4YM) and MSpec spectrograph.
Although the RGB stars were observed during excellent observing conditions
(seeing<1"), the HB observations were obtained in generally poor sky
conditions with seeing >1.5". The HR13 VLT-FLAMES data were obtained
between 2014 July 03 and August 01 and the HR21 data were obtained
between 2015 June 22 and July 26. Both data sets were binned 1x1 with
the HR13 and HR21 spanning 6115-6395 Å and 8482-8982 Å at
R∼26400 and 18000, respectively.
Objects:
-----------------------------------------------
RA (ICRS) DE Designation(s)
-----------------------------------------------
18 13 38.88 -31 49 35.2 NGC 6569 = GCl 91
-----------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 172 85 M2FS Star Identifiers, Coordinates, Photometry,
and Velocities
table3.dat 172 788 FLAMES Star Identifiers, Coordinates,
Photometry, and Velocities
table4.dat 58 19 M2FS RGB Cluster Member Model Atmosphere
Parameters
table5.dat 98 19 M2FS RGB Cluster Member Abundance Ratios and
Uncertainties: Oxygen to Calcium
table6.dat 101 19 M2FS RGB Cluster Member Abundance Ratios and
Uncertainties: Chromium to Europium
table7.dat 82 106 FLAMES RGB and HB Calcium Triplet Metallicity
Data for Cluster Members
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See also:
VII/202 : Globular Clusters in the Milky Way (Harris, 1997)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
II/337 : VISTA Variables in the Via Lactea Survey DR1 (Saito+, 2012)
II/348 : VISTA Variable in the Via Lactea Survey DR2 (Minniti+, 2017)
J/MNRAS/361/272 : JHKs photometry of 4 Bulge globular clusters
(Valenti+, 2005)
J/AJ/133/1287 : JHK photometry of 24 Galactic globular clusters
(Valenti+, 2007)
J/A+A/486/177 : Bulge field stars from FLAMES-GIRAFFE spectra
(Zoccali+, 2008)
J/MNRAS/383/183 : CaII triplet of RGB from VLT/FLAMES obs. (Battaglia+, 2008)
J/A+A/517/A81 : 2nd and 3d parameters of HB of globular clusters
(Gratton+, 2010)
J/MNRAS/402/1729 : JHK photometry of 36 Galactic globular clusters
(Valenti+ 2010)
J/A+A/540/A27 : Spectroscopy in Galactic globular clusters (Saviane+, 2012)
J/A+A/563/A76 : CaII triplet equivalent widths in 30 globulars
(Mauro+, 2014)
J/A+A/590/A9 : RGB stars in Galactic GC stellar parameters (Dias+, 2016)
Byte-by-byte Description of file: table2.dat table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- Member Member type
18- 33 A16 --- 2MASS 2MASS catalog identifier (HHMMSSss+DDMMSSs)
35 A1 --- f_2MASS [a] Flag on 2MASS (1)
37- 46 F10.6 deg RAdeg2M ? 2MASS Right Ascension in decimal degrees
(J2000)
48- 57 F10.6 deg DEdeg2M ? 2MASS Declination in decimal degrees (J2000)
59- 64 F6.3 mag Jmag2M [9.465/15.548]? 2MASS J band magnitude
66- 71 F6.3 mag Ksmag2M [8.027/14.865]? 2MASS Ks band magnitude
73- 92 A20 --- VVV VVV catalog identifier (JHHMMSS.ss+DDMMSS.ss)
94 A1 --- f_VVV [a] Flag on VVV (1)
96-105 F10.6 deg RAdegV ? VVV Right Ascension in decimal degrees (J2000)
107-116 F10.6 deg DEdegV ? VVV Declination in decimal degrees (J2000)
118-123 F6.3 mag JmagV [9.463/17.897]? VVV J band magnitude
125-130 F6.3 mag KsmagV [8.23/17.406]? VVV Ks band magnitude
132-144 A13 --- VLT VLT star name (only in Table 3)
146-152 F7.3 deg RAdegVL ? VLT Right Ascension in decimal degrees (J2000)
(only in Table 3)
154-161 F8.4 deg DEdegVL ? VLT Declination in decimal degrees (J2000)
(only in Table 3)
163-168 F6.1 km/s HRV [-378.8/255.3] Heliocentric radial velocity
170-172 F3.1 km/s e_HRV [0/6.1] Error in HRV
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Note (1): Flag as follows:
a = Observed with both M2FS and FLAMES.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- 2MASS 2MASS catalog identifier (HHMMSSss+DDMMSSs)
18- 37 A20 --- VVV VVV catalog identifier (JHHMMSS.ss+DDMMSS.ss)
39- 42 I4 K Teff [4075/4525] Effective temperature
44- 47 F4.2 [cm/s2] logg [0.75/1.75] Surface gravity (in cgs units)
49- 53 F5.2 [-] [Fe/H] [-0.96/-0.75] Metallicity (in dex)
55- 58 F4.2 km/s ksi [1.65/2.1] Microturbulence velocity ξmic
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- 2MASS 2MASS catalog identifier (HHMMSSss+DDMMSSs)
18- 37 A20 --- VVV VVV catalog identifier (JHHMMSS.ss+DDMMSS.ss)
39- 42 F4.2 [-] [O/Fe] [0.02/0.83]? [O/Fe] abundance (in dex)
44- 47 F4.2 [-] e_[O/Fe] [0.1]? Uncertainty in [O/Fe] (in dex)
49- 53 F5.2 [-] [Na/Fe] [-0.14/0.63] [Na/Fe] abundance (in dex)
55- 58 F4.2 [-] e_[Na/Fe] [0.05/0.11]? Uncertainty in [Na/Fe] (in dex)
60- 63 F4.2 [-] [Mg/Fe] [0.31/0.59] [Mg/Fe] abundance (in dex)
65- 68 F4.2 [-] e_[Mg/Fe] [0.05/0.07]? Uncertainty in [Mg/Fe] (in dex)
70- 73 F4.2 [-] [Al/Fe] [0.31/0.91] [Al/Fe] abundance (in dex)
75- 78 F4.2 [-] e_[Al/Fe] [0.07/0.14]? Uncertainty in [Al/Fe] (in dex)
80- 83 F4.2 [-] [Si/Fe] [0.15/0.48] [Si/Fe] abundance (in dex)
85- 88 F4.2 [-] e_[Si/Fe] [0.07/0.14]? Uncertainty in [Si/Fe] (in dex)
90- 93 F4.2 [-] [Ca/Fe] [0.07/0.42] [Ca/Fe] abundance (in dex)
95- 98 F4.2 [-] e_[Ca/Fe] [0.05/0.07]? Uncertainty in [Ca/Fe] (in dex)
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- 2MASS 2MASS catalog identifier (HHMMSSss+DDMMSSs)
18- 37 A20 --- VVV VVV catalog identifier (JHHMMSS.ss+DDMMSS.ss)
39- 43 F5.2 [-] [Cr/Fe] [-0.27/0.3]? [Cr/Fe] abundance (in dex)
45- 48 F4.2 [-] e_[Cr/Fe] [0.07/0.11]? Uncertainty in [Cr/Fe] (in dex)
50- 54 F5.2 [-] [FeI/H] [-0.97/-0.75] [FeI/H] abundance (in dex)
56- 59 F4.2 [-] e_[FeI/H] [0.1/0.1] Uncertainty in [FeI/H] (in dex)
61- 65 F5.2 [-] [FeII/H] [-0.95/-0.75] [FeII/H] abundance (in dex)
67- 70 F4.2 [-] e_[FeII/H] [0.11/0.13] Uncertainty in [FeII/H] (in dex)
72- 76 F5.2 [-] [Ni/Fe] [-0.2/0] [Ni/Fe] abundance (in dex)
78- 81 F4.2 [-] e_[Ni/Fe] [0.05/0.1] Uncertainty in [Ni/Fe] (in dex)
83- 86 F4.2 [-] [LaII/Fe] [0.18/0.68] [LaII/Fe] abundance (in dex)
88- 91 F4.2 [-] e_[LaII/Fe] [0.1/0.12] Uncertainty in [LaII/Fe] (in dex)
93- 96 F4.2 [-] [EuII/Fe] [0.37/0.88]? [EuII/Fe] abundance (in dex)
98-101 F4.2 [-] e_[EuII/Fe] [0.09/0.12]? Uncertainty in [EuII/Fe] (in dex)
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Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- 2MASS 2MASS catalog identifier (HHMMSSss+DDMMSSs)
18- 37 A20 --- VVV VVV catalog identifier (JHHMMSS.ss+DDMMSS.ss)
39- 51 A13 --- VLT VLT star name
53- 56 F4.2 0.1nm EW(8542) [2.67/4.34]? Ca II 8542Å equivalent width
(Å)
58- 61 F4.2 0.1nm EW(8662) [2.07/3.32]? Ca II 8662Å equivalent width
(Å)
63- 66 F4.2 0.1nm SigmaEW [4.86/7.55]? Summed Ca II equivalent width
ΣEW (Å) (1)
68- 71 F4.2 0.1nm W' [4.47/5.4]? Reduced equivalent width (Å) (1)
73- 77 F5.2 [Sun] [Fe/H] [-1.19/-0.5]? Metallicity
79- 82 F4.2 [Sun] e_[Fe/H] [0.01/0.56]? Uncertainty in [Fe/H]
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Note (1): Where ΣEW=EW(8542)+EW(8662) and
W'=ΣEW-0.385[KS(HB)-KS].
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 05-Oct-2018