J/A+A/677/A35 15 SMC cluster VI photometry (Saroon+, 2023)
The VISCACHA survey.
VIII. Chemical evolution history of Small Magellanic Cloud west halo clusters.
Saroon S., Dias B., Tsujimotto T., Parisi M.C., Maia F., Kerber L.,
Bekki K., Minniti D., Oliveira R.A.P., Westera P., Katime Santrich O.J.,
Bica E., Sanmartim D., Correa Quint B., Fraga L.
<Astron. Astrophys. 677, A35 (2023)>
=2023A&A...677A..35S 2023A&A...677A..35S (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Associations, stellar ; Photometry, CCD ;
Optical
Keywords: galaxies: dwarf - galaxies : interactions - Magellanic Clouds -
galaxies: clusters: general
Abstract:
The chemical evolution history of the Small Magellanic Cloud (SMC) has
been a matter of debate for decades. The challenges in understanding
the SMC chemical evolution are related to a very slow star formation
rate (SFR) combined with bursts triggered by the multiple interactions
between the SMC and the Large Magellanic Cloud, a significant
(∼0.5dex) metallicity dispersion for the SMC cluster population
younger than about 7.5Gyr, and multiple chemical evolution models
tracing very different paths through the observed age-metallicity
relation of the SMC. There is no doubt that these processes were
complex. Therefore, a step-by-step strategy is required in order to
better understand the SMC chemical evolution. We adopted an existing
framework to split the SMC into regions on the sky, and we focus on
the west halo in this work, which contains the oldest and most
metal-poor stellar populations and is moving away from the SMC, that
is, in an opposite motion with respect to the Magellanic Bridge. We
present a sample containing ∼60% of all west halo clusters to
represent the region well, and we identify a clear age-metallicity
relation with a tight dispersion that exhibits a 0.5dex metallicity
dip about 6Gyr ago. We ran chemical evolution models and discuss
possible scenarios to explain this metallicity dip, the most likely
being a major merger accelerating the SFR after the event. This merger
should be combined with inefficient internal gas mixing within the SMC
and different SFRs in different SMC regions because the same
metallicity dip is not seen in the AMR of the SMC combining clusters
from all regions. We try to explain the scenario to better understand
the SMC chemo-dynamical history.
Description:
Photometric parameters for 15 clusters in the SMC west halo region is
given. The following clusters have been observed using the the 4.1 m
Southern Astronomical Research (SOAR) telescope, which has a Ground
Layer Adaptive Optics (GLAO) module. The data is collected based on
observations obtained at SOAR (projects SO2016B-018, SO2017B-014,
CN2018B-012, SO2019B-019, SO2020B-019, SO2021B-017) for the VISCACHA
survey.
Objects:
-----------------------------------------------------------
RA (2000) DE Designation(s)
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00 52 37.99 -72 48 01.0 SMC = Small Magellanic Cloud
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 61 15 Best fitted parameters for the 15 SMC west halo
clusters analysed in this work
k9.dat 83 3656 K9 cluster positions and magnitudes
b1.dat 83 1143 B1 cluster positions and magnitudes
ngc152.dat 83 5408 NGC152 cluster positions and magnitudes
b2.dat 83 730 B2 cluster positions and magnitudes
k6.dat 83 1500 K6 cluster positions and magnitudes
k8.dat 83 2047 K8 cluster positions and magnitudes
b4.dat 83 1891 B4 cluster positions and magnitudes
k7.dat 83 2804 K7 cluster positions and magnitudes
l14.dat 83 3393 L14 cluster positions and magnitudes
k11.dat 83 1413 K11 cluster positions and magnitudes
l2.dat 83 771 L2 cluster positions and magnitudes
hw1.dat 83 1531 HW1 cluster positions and magnitudes
am3.dat 83 327 AM3 cluster positions and magnitudes
hw5.dat 83 1996 HW5 cluster positions and magnitudes
ngc121.dat 83 5697 NGC121 cluster positions and magnitudes
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- Cluster Cluster name
8- 12 F5.2 Gyr Age Age of the cluster derived from
the best fitted isochrone
14- 17 F4.2 Gyr e_Age Error in the age estimate
19- 23 F5.2 --- [Fe/H] Metallicity of the cluster derived from
the best fitted isochrone
25- 29 F5.3 --- e_[Fe/H] Error in the metallicity estimate
31- 34 F4.1 kpc D Distance of the cluster derived from
the best fitted isochrone
36- 39 F4.2 kpc e_D Error in the distance estimate
41- 44 F4.2 mag Av Reddening value of the cluster derived from
the best fitted
46- 50 F5.3 mag e_Av Error in the reddening estimate
52- 61 A10 --- Table Name of the table with VI photometry
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Byte-by-byte Description of file: am*.dat b*.dat hw*.dat k*.dat ngc*.dat l*.dat
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Bytes Format Units Label Explanations
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1- 18 F18.14 deg RAdeg Right Ascension (J2000)
20- 37 F18.14 deg DEdeg Declination (J2000)
39- 47 F9.6 mag Vmag ?=- V magnitude
49- 60 F12.10 mag e_Vmag ?=- Error in V magnitude
62- 70 F9.6 mag Imag ?=- I magnitude
72- 83 F12.10 mag e_Imag ?=- Error in I magnitude
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Acknowledgements:
S. Saroon, saroonsasi19(at)gmail.com
References:
Maia et al., Paper I 2019MNRAS.484.5702M 2019MNRAS.484.5702M
Santos et al., Paper II 2020MNRAS.498..205S 2020MNRAS.498..205S
Dias et al., Paper III 2021A&A...647L...9D 2021A&A...647L...9D
Dias et al., Paper IV 2022MNRAS.512.4334D 2022MNRAS.512.4334D
Bica et al., Paper V 2022MNRAS.517L..41B 2022MNRAS.517L..41B
Rodriguez et al., Paper VI 2023MNRAS.519.3357R 2023MNRAS.519.3357R
(End) Patricia Vannier [CDS] 15-Jul-2023