J/A+A/666/A80 Star clusters and fields in the LMC (Narloch+, 2022)
Metallicities and ages for star clusters and their surrounding fields
in the Large Magellanic Cloud.
Narloch W., Pietrzynski G., Gieren W., Piatti A.E., Karczmarek P.,
Gorski M., Graczyk D., Smolec R., Hajdu G., Suchomska K., Zgirski B.,
Wielgorski P., Pilecki B., Taormina M., Kaluszynski M., Pych W.,
Rojas Garcia G., Lewis M.O.
<Astron. Astrophys. 666, A80 (2022)>
=2022A&A...666A..80N 2022A&A...666A..80N (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Galaxies, photometry ; Photometry, uvby
Keywords: methods: observational - techniques: photometric -
galaxies: individual: Large Magellanic Cloud -
galaxies: star clusters: general - galaxies: abundances
Abstract:
We study 147 star clusters in the Large Magellanic Cloud (LMC) in
order to determine their mean metallicities and ages, as well as the
mean metallicities of 80 surrounding fields. We construct an
age-metallicity relation (AMR) for the clusters in the LMC.
For this purpose, we use Stroemgren photometry obtained with SOI
camera on the 4.1m SOAR telescope. We derive metallicities of
individual stars utilizing a calibration of Stroemgren (b-y) and m1
colors with metallicities from the literature. Cluster ages are
determined from the isochrone fitting.
We find the mean metallicity and age for 110 star clusters and for the
remaining 37 we provide an age estimation only. Tothe best of our
knowledge, for 29 clusters from our sample we provide both metallicity
and age for the first time, while for 66 clusters we provide a first
determination of the metallicity, and for 43 clusters the first
estimation of the age. We also calculate the mean metallicities for
stars from 80 fields around the clusters. The results are then
analyzed for spatial metallicity and age distributions of clusters in
the LMC, as well as AMR for them. The old, metal-poor star clusters
occur both in and out of the LMC bar region, while intermediate-age
clusters are located mostly outside of the bar. The majority of star
clusters younger than 1Gyr are located in the bar region. We find
good agreement between our AMR and theoretical models of the LMC
chemical enrichment, as well as with AMRs for clusters from the
literature. Next, we take advantage of 26 stellar clusters from our
sample which host Cepheid variables and use them as an independent
check of the correctness of our age determination procedure. We use
period-age relations for Cepheids to calculate the mean age of a
given cluster and compare it with the age obtained from isochrone
fitting. We find good agreement between these ages especially for
models taking into account additional physical processes, e.g.,
rotation. We also compare the AMR of the LMC and Small Magellanic
Cloud derived in a uniform way, and note that they indicate possible
former interaction between these two galaxies. The Stroemgren
photometry obtained for this study is made publicly available.
Description:
The catalog of the Stroemgren photometry for stars for which all three
Stroemgren vby filters were available and subsequently color indices
(b-y) and m1 could be calculated. Data were collected with 4.1-m SOAR
telescope placed in Cerro Pachon in Chile and equipped with the SOI
camera with field of view of 5.26'x5.26' and pixel scale of 0.154"/pix
during two runs: December 17-19, 2008 and January 16-18, 2009.
Photometric errors are presented in two columns, depending on the
method used for their evaluation: i) the DAOPHOT package or ii) full
error propagation of the transformation equations.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 135 604203 Stroemgren photometry of stars in the LMC
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/AJ/117/238 : LMC extended catalog (Bica+, 1999)
J/AcA/49/521 : OGLE LMC star clusters BVI photometry (Pietrzynski+, 1999)
J/A+A/602/A89 : Star clusters in the Magellanic Clouds (Perren+, 2017)
J/A+A/517/A50 : Ages & luminosities of young SMC/LMC star clusters
(Glatt+, 2010)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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2- 10 F9.6 deg RAdeg Right ascension (J2000)
12- 21 F10.6 deg DEdeg Declination (J2000)
25- 32 F8.3 pix Xpos X coordinate on the image
36- 43 F8.3 pix Ypos Y coordinate on the image
47- 48 I2 --- Field Ordinal number of the field of stars
52- 57 F6.3 mag Vmag V magnitude
60- 64 F5.3 mag e_VmagDAO Photometric error of V magnitude resulting
from DAOPHOT
67- 71 F5.3 mag e_Vmag Photometric error of V magnitude resulting
from full propagation of the transformation
equation to the standard system
75- 80 F6.3 mag (b-y) Stroemgren (b-y) color
83- 87 F5.3 mag e_(b-y)DAO Photometric error of (b-y) color resulting
from DAOPHOT
90- 94 F5.3 mag e_(b-y) Photometric error of (b-y) color resulting
from full propagation of the transformation
equation to the standard system
98-103 F6.3 mag m1 Stroemgren m1 color index
106-110 F5.3 mag e_m1DAO Photometric error of m1 index resulting
from DAOPHOT
113-117 F5.3 mag e_m1 Photometric error of m1 index resulting
from full propagation of the transformation
equation to the standard system
121-126 F6.3 --- CHI CHI parameter from DAOPHOT
129-135 F7.3 --- SHARP SHARP parameter from DAOPHOT
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Acknowledgements:
Weronika Narloch, wnarloch(at)astro-udec.cl
(End) Patricia Vannier [CDS] 14-Jul-2022