J/ApJ/845/56 Star clusters automatically detected in the LMC (Bitsakis+, 2017)
A novel method to automatically detect and measure the ages of star clusters in
nearby galaxies: application to the Large Magellanic Cloud.
Bitsakis T., Bonfini P., Gonzalez-Lopezlira R.A., Ramirez-Siordia V.H.,
Bruzual G., Charlot S., Maravelias G., Zaritsky D.
<Astrophys. J., 845, 56 (2017)>
=2017ApJ...845...56B 2017ApJ...845...56B
ADC_Keywords: Associations, stellar ; Magellanic Clouds ; Surveys
Keywords: catalogs; galaxies: star clusters: general; Magellanic Clouds;
methods: statistical
Abstract:
We present our new, fully automated method to detect and measure the
ages of star clusters in nearby galaxies, where individual stars can
be resolved. The method relies purely on statistical analysis of
observations and Monte-Carlo simulations to define stellar
overdensities in the data. It decontaminates the cluster
color-magnitude diagrams and, using a revised version of the Bayesian
isochrone fitting code of Ramirez-Siordia+ (2017, in prep.), estimates
the ages of the clusters. Comparisons of our estimates with those from
other surveys show the superiority of our method to extract and
measure the ages of star clusters, even in the most crowded fields. An
application of our method is shown for the high-resolution, multiband
imaging of the Large Magellanic Cloud. We detect 4850 clusters in the
7deg2 we surveyed, 3451 of which have not been reported before. Our
findings suggest multiple epochs of star cluster formation, with the
most probable occurring ∼310Myr ago. Several of these events are
consistent with the epochs of the interactions among the Large and
Small Magellanic Clouds, and the Galaxy, as predicted by N-body
numerical simulations. Finally, the spatially resolved star cluster
formation history may suggest an inside-out cluster formation scenario
throughout the LMC, for the past 1Gyr.
Description:
The archival data used in this work were acquired from several diverse
large surveys, which mapped the Magellanic Clouds at various bands.
Simons+ (2014AdSpR..53..939S 2014AdSpR..53..939S) composed a mosaic using archival data
from the Galaxy Evolution Explorer (GALEX) at the near-ultraviolet
(NUV) band (λeff=2275Å). The mosaic covers an area of
15deg2 on the LMC. the central ∼3x1deg2 of the LMC (the
bar-region) was later observed by the Swift Ultraviolet-Optical
Telescope (UVOT) Magellanic Clouds Survey (SUMAC;
Siegel+ 2014AJ....148..131S 2014AJ....148..131S).
The optical data used here are from the Magellanic Cloud Photometric
Survey (MCPS; Zaritsky+ 2004, J/AJ/128/1606). These authors observed
the central 64deg2 of the LMC with 3.8-5.2 minute exposures at the
Johnson U, B, V, and Gunn i filters of the Las Campanas Swope Telescope.
Meixner+ (2006, J/AJ/132/2268) performed a uniform and unbiased
imaging survey of the LMC (called Surveying the Agents of a Galaxy's
Evolution, or SAGE), covering the central 7deg2 with both the
Infrared Array Camera (IRAC) and the Multiband Imaging Photometer
(MIPS) on-board the Spitzer Space Telescope.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 71 4850 Star cluster catalog
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See also:
VII/183 : The Cluster System of the LMC (Kontizas+ 1990)
VI/102 : Geneva stellar evolution tracks and isochrones (Lejeune+, 2001)
II/305 : SAGE LMC and SMC IRAC Source Catalog (IPAC 2009)
J/A+AS/110/533 : Clusters and field stars in LMC. I. (Linde+, 1995)
J/AJ/116/723 : LMC star clusters ages and metallicity (Bica+ 1998)
J/AJ/117/2244 : HST color-magnitude diagrams of the LMC (Olsen, 1999)
J/AJ/119/1748 : WFPC 2 imaging of young LMC clusters (Keller+, 2000)
J/AcA/50/337 : OGLE LMC star clusters (Pietrzynski+, 2000)
J/AJ/128/1606 : Magellanic Clouds Photometric Survey: LMC (Zaritsky+, 2004)
J/MNRAS/357/645 : LMC far-UV HST observations (Almoznino+, 2005)
J/AJ/132/2268 : SAGE calibration stars (Meixner+, 2006)
J/MNRAS/389/678 : Extended objects in Magellanic Clouds (Bica+, 2008)
J/AJ/138/1243 : The star formation history of the LMC (Harris+, 2009)
J/A+A/503/469 : Compact clusters in LMC catalogue of stars (Liu+, 2009)
J/A+A/517/A50 : Ages & luminosities of SMC/LMC star clusters (Glatt+, 2010)
J/MNRAS/403/1213 : Tracers of stellar mass-loss. I. (Gonzalez-Lopezlira+, 2010)
J/AJ/142/48 : LMC star clusters structural parameters (Werchan+, 2011)
J/MNRAS/425/3085 : CCD CT1 data of stars in the field of B119 (Piatti+, 2012)
J/ApJ/749/124 : Spectroscopy on LMC clusters (Colucci+, 2012)
J/ApJ/751/122 : Ages and masses for 920 LMC clusters (Popescu+, 2012)
J/A+A/555/A131 : Fundamental param. of star clusters in LMC (Palma+, 2013)
J/MNRAS/430/676 : Massive clusters in the LMC (Baumgardt+, 2013)
J/MNRAS/436/136 : Ages and masses of LMC clusters (de Grijs+, 2013)
J/MNRAS/454/839 : VMC survey. XVI. (Piatti+, 2015)
J/A+A/586/A41 : LMC star clusters catalog (Palma+, 2016)
J/A+A/606/A21 : LMC bar star clusters (Piatti, 2017)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- CID Cluster identifier
10- 19 F10.7 deg RAdeg [68.9/91.5] Right Ascension (J2000)
21- 31 F11.7 deg DEdeg [-72.5/-65.1] Declination (J2000)
33- 41 F9.7 deg Rad [0.004/0.03] Cluster radius
43- 51 F9.7 [yr] logAge [6.7/9.8] Log cluster age
53- 61 F9.7 [yr] b_logAge [6.7/9.7] Lower logAge boundary
63- 71 F9.7 [yr] B_logAge [6.8/10] Upper logAge boundary
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 08-Mar-2018