J/A+A/607/A44 FLAMES observations of NGC6535 (Bragaglia+, 2017)
NGC 6535: the lowest mass Milky Way globular cluster with a Na-O
anti-correlation? Cluster mass and age in the multiple population context.
Bragaglia A., Carretta E., D'Orazi V., Sollima A., Donati P., Gratton R.G.,
Lucatello S.
<Astron. Astrophys. 607, A44 (2017)>
=2017A&A...607A..44B 2017A&A...607A..44B (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Abundances ; Spectroscopy
Keywords: stars: abundances - stars: atmospheres - stars: Population II -
open clusters and associations: individual: NGC 6535 -
globular clusters: general
Abstract:
To understand globular clusters (GCs) we need to comprehend how their
formation process was able to produce their abundance distribution of
light elements. In particular, we need to figure out which stars
imprinted the peculiar chemical signature of GCs. One of the best way
is to study the light-element anti-correlations in a large sample of
GCs, analysed homogeneously. As part of our spectroscopic survey of
GCs with FLAMES, we present here the results of our study of about 30
red giant member stars in the low-mass, low-metallicity Milky Way
cluster NGC 6535. We measured its metallicity (finding [Fe/H]=-1.95,
rms=0.04dex in our homogeneous scale) and other elements, in
particular we concentrate here on O and Na abundances. These elements
define the normal Na-O anti-correlation of classical GCs, making NGC
6535 perhaps the lowest mass cluster with confirmed presence of
multiple populations. We updated the census of Galactic and
extragalactic GCs for which a statement on the presence or absence of
multiple populations can be made on the basis of high-resolution
spectroscopy preferentially, or photometry and low-resolution
spectroscopy otherwise, discussing the importance of mass and age of
the clusters.
Description:
We used FLAMES@VLT spectra of 45 stars in the globular cluster NGC
6535 to measure radial velocity and infer cluster membership, to
derive atmospheric parameters and abundances (in particular of the
light elements O and Na). We find a O-Na anticorrelation, as normal
for a GC. We also compile a list of clusters known to host (or not)
multiple populations on the basis of their chemistry.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 91 45 Basic information on observed stars
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See also:
J/AJ/121/916 : HST obs. of NGC 2298, 5897, 6535, and 6626 (Testa+, 2001)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- ID Star ID (from Testa et al., 2001,
Cat. J/AJ/121/916)
9 A1 --- Instr UVES (U) or GIRAFFE (G) spectrum acquired
11- 12 I2 h RAh Right ascension (J2000.0)
14- 15 I2 min RAm Right ascension (J2000.0)
17- 21 F5.2 s RAs Right ascension (J2000.0)
23 A1 --- DE- Declination sign (J2000.0)
24- 25 I2 deg DEd Declination (J2000.0)
27- 28 I2 arcmin DEm Declination (J2000.0)
30- 34 F5.2 arcsec DEs Declination (J2000.0)
36- 41 F6.3 mag Vmag V magnitude
43- 47 F5.3 mag V-I (V-I) colour index
49- 54 F6.3 mag Ksmag ?=0 2MASS Ks magnitude
56- 61 F6.2 km/s HRV Heliocentric radial velocity
63- 66 F4.2 km/s e_HRV Error on HRV
68- 70 A3 --- Memb Membership flag (M/NM?/NM)
72- 87 A16 --- 2MASS 2MASS identification
89- 91 A3 --- q_2MASS 2MASS quality flag for JHK
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Acknowledgements:
Angela Bragaglia, angela.bragaglia(at)oabo.inaf.it
(End) Patricia Vannier [CDS] 02-Aug-2017