J/A+A/664/A168 CaII spectroscopy of SMC red giants. VI. (De Bortoli+, 2022)
Ca II triplet spectroscopy of Small Magellanic Cloud Red Giants.
VI. Analysis of chemical properties of the main body.
De Bortoli B.J., Parisi M.C., Bassino L.P., Geisler D., Dias B., Gimeno G.,
Angelo M.S., Mauro F.
<Astron. Astrophys. 664, A168 (2022)>
=2022A&A...664A.168D 2022A&A...664A.168D (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Stars, giant ; Radial velocities ; Optical ;
Equivalent widths ; Abundances, [Fe/H]
Keywords: galaxies: star clusters: general - Magellanic Clouds -
stars: abundances
Abstract:
We aim to analyze the chemical evolution of the Main Body of the SMC,
adding six additional clusters to previously published samples, based
on homogeneously determined and accurate metallicities.
We derived radial velocities and CaII Triplet (CaT) metallicity of
more than 150 red giants stars in six SMC star clusters and their
surrounding fields, with the instrument GMOS on GEMINI-S. The mean
cluster radial velocity and metallicity were obtained with mean errors
of 2.2km/s and 0.03dex, while the mean field metallicities have a
mean error of 0.13dex. We add this information to that available for
another 51 clusters and 30 fields with CaT metallicities on the same
scale. Using this expanded sample we analize the chemical properties
of the SMC Main Body, defined as the inner 3.4 degrees in semimajor
axis.
We found a high probability that the metallicity distribution of the
Main Body clusters is bimodal with a metal-rich and a metal-poor
cluster group, having mean metallicities with a dispersion of
µ=-0.80, σ=0.06 and µ = -1.15, σ=0.10dex,
respectively. On the other hand,Main Body field stars show a unimodal
metallicity distribution peaking at [Fe/H]~-1 and dispersion of 0.3.
Neither metal-rich nor metal-poor clusters present a metallicity
gradient. However the full Main Body cluster sample and field stars
have a negative metallicity gradient consistent with each other, but
the one corresponding to clusters has a large error due to the large
metallicity dispersion present in the clusters studied in that region.
Metal-rich clusters present a clear age-metallicity relation, while
metal-poor clusters present no chemical enrichment throughout the life
of the galaxy.
We present observational evidence that the chemical enrichment is
complex in the SMC Main Body. Two cluster groups with potential
different origins could be coexisting in the Main Body. More data with
precise and homogeneous metallicities and distances are needed and
dynamical simulations are required to understand possible different
origins for the two possible cluster groups.
Description:
Using CaII Triplet lines we have determined the mean RV and
metallicity of 6 clusters and 6 fields in the SMC.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 59 6 Selected SMC cluster sample
table2.dat 75 124 Measured parameters for the observed RGB stars
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See also:
J/AJ/138/517 : CaII spectroscopy of SMC red giants (Parisi+, 2009)
J/AJ/139/1168 : CaII spectroscopy of SMC fields stars (Parisi+, 2010)
J/AJ/149/154 : CaII spectroscopy of SMC red giants. III. (Parisi+, 2015)
J/AJ/152/58 : CaII spectroscopy of SMC red giants. IV. (Parisi+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Cluster Cluster name
6- 7 I2 h RAh Right ascension (J2000.0)
9- 10 I2 min RAm Right ascension (J2000.0)
12- 15 F4.1 s RAs Right ascension (J2000.0)
17 A1 --- DE- Declination sign (J2000.0)
18- 19 I2 deg DEd Declination (J2000.0)
21- 22 I2 arcmin DEm Declination (J2000.0)
24- 25 I2 arcsec DEs Declination (J2000.0)
27- 31 F5.3 deg a Projected distance to the SMC centre
33 A1 --- l_Age [~] Limit flag on Age
34- 36 F3.1 Gyr Age Age
38- 40 F3.1 Gyr e_Age ? rms uncertainty on Age
42 I1 --- r_Age [1/3] Age reference (1)
44- 45 I2 --- N Number of members in table2.dat
47- 59 A13 --- SName Simbad name
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Note (1): References as follows:
1 = Parisi et al. (2014AJ....147...71P 2014AJ....147...71P)
2 = Bica et al. (2022, in prep.)
3 = Dias et al. (2014A&A...561A.106D 2014A&A...561A.106D, Cat. J/A+A/561/A106)
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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- 4 A4 --- Cluster Cluster name
8- 9 I2 --- ID Cluster member identification number
11- 12 I2 h RAh Right Ascension (J2000)
14- 15 I2 min RAm Right Ascension (J2000)
17- 21 F5.2 s RAs Right Ascension (J2000)
23 A1 --- DE- Declination sign (J2000)
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 34 F5.2 arcsec DEs Declination (J2000)
36- 40 F5.1 km/s RV Heliocentric radial velocity
42- 45 F4.1 km/s e_RV The 1σ error in RV
47- 51 F5.2 mag g-gHB ? Brightness difference between star and
cluster's horizontal branch
53- 57 F5.2 0.1nm SigmaW ? Summed CaII equivalent width (1)
59- 62 F4.2 0.1nm e_SigmaW ? The 1σ error in SigmaW
64- 68 F5.2 --- [Fe/H] ? Metallicity
70- 73 F4.2 --- e_[Fe/H] ? The error in Metallicity
75 A1 --- C/F [C/F] Cluster (C) or field (F) star
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Note (1): Where SigmaW = EW(8498) + EW(8542) + EW(8662).
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Acknowledgements:
Bruno De Bortoli, brudebo.444(at)gmail.com
References:
Parisi et al., Paper I 2009AJ....138..517P 2009AJ....138..517P, Cat. J/AJ/138/517
Parisi et al., Paper II 2010AJ....139.1168P 2010AJ....139.1168P, Cat. J/AJ/139/1168
Parisi et al., Paper III 2015AJ....149..154P 2015AJ....149..154P, Cat. J/AJ/149/154
Parisi et al., Paper IV 2016AJ....152...58P 2016AJ....152...58P, Cat. J/AJ/152/58
(End) Patricia Vannier [CDS] 07-Jun-2022