J/A+A/659/A122 Metallicity of NGC 6388 (Carretta+, 2022)
Metallicity of the globular cluster NGC 6388 based on high-resolution spectra of
more than 160 giant stars.
Carretta E., Bragaglia A.
<Astron. Astrophys. 659, A122 (2022)>
=2022A&A...659A.122C 2022A&A...659A.122C (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Abundances, [Fe/H] ; Stars, population II ;
Optical
Keywords: stars: abundances - stars: atmospheres - stars: Population II -
globular clusters: general - globular clusters: individual: NGC 6388
Abstract:
NGC 6388 is one of the most massive Galactic globular clusters (GC)
and it is an old, metal-rich, Galactic bulge cluster. By exploiting
previous spectroscopic observations we were able to bypass the
uncertainties in membership related to the strong field stars
contamination. We present the abundance analysis of 12 new giant stars
with UVES spectra and 150 giants with GIRAFFE spectra acquired at the
ESO-VLT. We derived radial velocities, atmospheric parameters and iron
abundances for all stars. When combined to previous data, we obtain a
grand total of 185 stars homogeneously analysed in NGC 6388 from
high-resolution spectroscopy. The average radial velocity of the 185
stars is 81.2±0.7, rms=9.4km/s. We obtain an average metallicity
[Fe/H]=-0.480dex, rms=0.045 dex (35 stars) and [Fe/H]=-0.488dex,
rms=0.040dex (150 stars) from the UVES and GIRAFFE samples,
respectively. Comparing these values to internal errors in abundance,
we exclude the presence of a significant intrinsic metallicity spread
within the cluster. Since about a third of giants in NGC 6388 is
claimed to belong to the anomalous red giants in the HST pseudo-colour
map defining the so-called type-II GCs, we conclude that either
enhanced metallicity is not a necessary requisite to explain this
classification (as also suggested by the null iron spread for NGC 362)
or NGC 6388 is not a type-II globular cluster.
Description:
Spectroscopic atmospheric parameters (Teff, logg, [Fe/H]) and radial
velocities for a sample of more than 160 stars are presented for the
massive bulge globular cluster NGC 6388. When coupled with a previous
analysis, we have data for 185 giant stars in this cluster. No spread
in metallicity is detected.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 71 162 ID, positions, magnitudes, radial velocity of
the stars
table3.dat 61 162 Iron abundance (neutral and ionised)
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See also:
J/A+A/505/117 : Red giants abundances in 15 globular clusters (Carretta+, 2009)
J/ApJ/769/107 : RVs and [Fe/H] of star members of NGC 6388 (Lanzoni+, 2013)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Star Star ID
9- 15 A7 --- Sample Kind of spectrum (1)
17- 19 I3 --- S/N Signal-to-Noise ratio
21- 30 F10.6 deg RAdeg Right ascension (J2000.0)
32- 41 F10.6 deg DEdeg Declination (J2000.0)
43- 48 F6.3 mag Vmag WFI magnitude in V band
50- 55 F6.3 mag Bmag ? WFI magnitude in B band
57- 62 F6.3 mag Ksmag ? Ks magnitude from 2MASS
64 I1 --- WFI [0/1] WFI photometry present (=1) or not (=0)
66- 71 F6.2 km/s RV Radial velocity
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Note (1): Samples as follows:
us = UVES, present paper
H-B = archive, PI Henault-Brunet
C09 = Carretta et al. (2009A&A...505..117C 2009A&A...505..117C, Cat. J/A+A/505/117)
CAT = archive, PI Catelan
L13 = archive, Lanzoni et al. (2013ApJ...769..107L 2013ApJ...769..107L, Cat. J/ApJ/769/107)
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Star Star ID
9- 12 I4 K Teff Star Teff
14- 17 F4.2 [cm/s2] logg Star surface gravity
19- 23 F5.2 [-] [A/H] Metallicity of atmospheric model
25- 28 F4.2 km/s Vt Microturbulent velocity
30- 32 I3 --- o_FeI Number of FeI lines
34- 39 F6.3 [-] [Fe/H]I Neutral iron abundance
41- 45 F5.3 [-] rmsFeI rms of neutral iron abundance
47- 48 I2 --- o_FeII Number of FeII lines
50- 55 F6.3 [-] [Fe/H]II ? Ionised iron abundance
57- 61 F5.3 [-] rmsFeII rms of ionised iron abundance
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Acknowledgements:
Eugenio Carretta, eugenio.carretta(at)inaf.it
(End) E. Carretta [INAF-OAS Bologna, Italy], P. Vannier [CDS] 24-Nov-2021