J/ApJ/853/104 Ages of star clusters in SMC (Bitsakis+, 2018)
The distribution and ages of star clusters in the Small Magellanic Cloud:
constraints on the interaction history of the Magellanic Clouds.
Bitsakis T., Gonzalez-Lopezlira R.A., Bonfini P., Bruzual G., Maravelias G.,
Zaritsky D., Charlot S., Ramirez-Siordia V.H.
<Astrophys. J., 853, 104 (2018)>
=2018ApJ...853..104B 2018ApJ...853..104B
ADC_Keywords: Magellanic Clouds; Clusters, open; Cross identifications
Keywords: catalogs ; galaxies: star clusters: general ; Magellanic Clouds ;
methods: statistical
Abstract:
We present a new study of the spatial distribution and ages of the
star clusters in the Small Magellanic Cloud (SMC). To detect and
estimate the ages of the star clusters we rely on the new fully
automated method developed by Bitsakis+ (2017, J/ApJ/845/56). Our code
detects 1319 star clusters in the central 18deg2 of the SMC we
surveyed (1108 of which have never been reported before). The age
distribution of those clusters suggests enhanced cluster formation
around 240Myr ago. It also implies significant differences in the
cluster distribution of the bar with respect to the rest of the
galaxy, with the younger clusters being predominantly located in the
bar. Having used the same setup, and data from the same surveys as for
our previous study of the LMC, we are able to robustly compare the
cluster properties between the two galaxies. Our results suggest that
the bulk of the clusters in both galaxies were formed approximately
300Myr ago, probably during a direct collision between the two
galaxies. On the other hand, the locations of the young (≤50Myr)
clusters in both Magellanic Clouds, found where their bars join the HI
arms, suggest that cluster formation in those regions is a result of
internal dynamical processes. Finally, we discuss the potential causes
of the apparent outside-in quenching of cluster formation that we
observe in the SMC. Our findings are consistent with an evolutionary
scheme where the interactions between the Magellanic Clouds constitute
the major mechanism driving their overall evolution.
Description:
We have made use of archival data of the SMC at various bands.
Simons+ (2014AdSpR..53..939S 2014AdSpR..53..939S) presented the near-ultraviolet mosaic
(λeff=2275Å) of that galaxy obtained by the Galaxy
Evolution Explorer (GALEX). Holes in the GALEX coverage were
compensated for with the Swift Ultraviolet-Optical Telescope (UVOT)
Magellanic Clouds Survey (SUMAC; Siegel+ 2014AJ....148..131S 2014AJ....148..131S), which
imaged the central 3.8deg2 of the galaxy with deeper exposures of
3000s in all three NUV filters of the instrument (UVW1, UVW2, and UVM2).
Our infrared data come from the "Surveying the Agents of a Galaxy's
Evolution SMC survey" (SAGE-SMC; Gordon+ 2011AJ....142..102G 2011AJ....142..102G) that
mapped the full SMC (30deg2) with both the Infrared Array Camera
(IRAC) and the Multiband Imaging Photometer (MIPS) on board the
Spitzer Space Telescope.
Finally, we exploited the photometric information by Zaritsky+ (2002,
J/AJ/123/855), who presented the stellar catalog and extinction map of
the SMC, as part of the Magellanic Cloud Photometric Survey (MCPS).
They obtained 3.8-5.2 minute exposures of the central 18deg2 of the
SMC in the Johnson U, B, V, and Gunn i bands with the Las Campanas
Swope Telescope.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 96 1319 SMC star cluster catalog
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See also:
J/A+AS/125/229 : A standard stellar library (Lejeune+ 1997)
J/AJ/123/855 : Magellanic Clouds Photometric Survey: the SMC (Zaritsky+, 2002)
J/AJ/127/1531 : Star formation history of SMC (Harris+, 2004)
J/AJ/129/2701 : UBVRI photometry of SMC star clusters (Rafelski+, 2005)
J/A+A/452/179 : Ages of SMC young clusters and field stars (Chiosi+, 2006)
J/ApJ/658/345 : CRIc photometry of Magellanic Bridge Fields (Harris, 2007)
J/MNRAS/389/678 : Extended objects catalog in Magellanic Clouds (Bica+, 2008)
J/AJ/138/1243 : The star formation history of the LMC (Harris+, 2009)
J/A+A/517/A50 : Ages & luminosities of SMC/LMC star clusters (Glatt+, 2010)
J/MNRAS/430/676 : Massive clusters in the LMC (Baumgardt+, 2013)
J/A+A/597/A85 : NGC3627S and NGC3627N CO(1-0) data cubes (Beuther+, 2017)
J/ApJ/845/56 : Star clusters automatically detected in LMC (Bitsakis+, 2017)
J/A+A/616/A187 : SMC clusters age-dating + classification (Nayak+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- ID Catalog identifier
14- 23 F10.7 deg RAdeg [7.5/18.6] Right Ascension (J2000)
25- 35 F11.7 deg DEdeg [-74.5/-70.7] Declination (J2000)
37- 45 F9.7 deg Rad [0.006/0.03] Radius
47- 55 F9.7 [yr] logAge [6/10] Log of the age
57- 65 F9.7 [yr] e_logAge [6/10] Lower 16% uncertainty bound in logAge
67- 76 F10.7 [yr] E_logAge [6.8/10.2] Upper 84% uncertainty bound in logAge
78- 80 I3 --- B08 [31/542]? Bica+ (2008, J/MNRAS/389/678) catalog
number
82- 96 A15 --- Simbad SimbadName for the Bica+ (2008, J/MNRAS/389/678)
object; column added by CDS
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 30-Oct-2018