J/A+A/616/A187 SMC clusters age-dating & classification (Nayak+, 2018)
Star clusters in the Magellanic Clouds. II.
Age-dating, classification and spatio-temporal distribution of the SMC clusters.
Nayak P.K., Subramaniam A., Choudhury S., Sagar R.
<Astron. Astrophys. 616, A187 (2018)>
=2018A&A...616A.187N 2018A&A...616A.187N (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Associations, stellar
Keywords: Magellanic Clouds - galaxies: star clusters: general -
galaxies: star formation
Abstract:
We aim to estimate the age and reddening parameters of already
identified star clusters within the Small Magellanic Cloud (SMC) in a
consistent way using available photometric data, classify them based
on their mass and strength, and study their spatio-temporal
distribution. We have used a semi-automated quantitative method,
developed in the first paper of this series (Paper I), to estimate the
cluster parameters using the V and I band photometric data from the
Optical Gravitational Lensing Experiment (OGLE) III survey. We
estimated parameters of 179 star clusters (17 are newly parameterised)
and classified them into four groups. We present an online catalogue
of parameters as well as cleaned and isochrone-fitted colour magnitude
diagrams of 179 clusters. We compiled age information of 468 clusters
by combining previous studies with our catalogue, to study their
spatio-temporal distribution. Most of the clusters located in the
southern part of the SMC are in the age range 600Myr-1.25Gyr,
whereas, the clusters younger than 100Myr are mostly found in the
northern SMC, with the central SMC showing continuous cluster
formation. The peak of the cluster age distribution is identified at
130±35Myr, very similar to the Large Magellanic Cloud (LMC) in Paper
I. We suggest that the burst of cluster formation at 130Myr is due to
the most recent LMC-SMC interaction. 90% of the studied sample is
found to have mass <1700M☉, suggesting that the SMC is dominated
by low mass clusters. There is tentative evidence for compact clusters
in the LMC when compared to those in the Galaxy and the SMC. A
progressive shifting of cluster location from the south to north of
the SMC is identified in last ∼600Myr. The details of spatio-temporal
distribution of clusters presented in two videos as part of this study
can be used as a tool to constrain details of the recent LMC-SMC
interactions.
Description:
Parameters and classification of 179 SMC star clusters are presented.
For each star cluster right ascension, declination, radius, reddening,
log(age(yr)), classification, and estimated log(age(yr)) from other
studies are given.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 81 179 Parameters and classification for 179 star
clusters in the SMC
--------------------------------------------------------------------------------
See also:
J/MNRAS/389/678 : Catalogue of extended objects in Magellanic Clouds
(Bica+, 2008)
J/A+A/517/50 : Ages + luminosities of young SMC/LMC star clusters
(Glatt+, 2010)
J/A+A/452/179 : Ages of SMC young clusters and field stars (Chiosi+, 2006)
J/MNRAS/463/1446 : Star clusters in Magellanic Clouds (Nayak+, 2016)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
3- 10 A8 --- Name Cluster name
17 A1 --- n_Name [*] Note on Name (1)
20 I1 h RAh Right ascension (J2000.0)
22- 23 I2 min RAm Right ascension (J2000.0)
25- 26 I2 s RAs Right ascension (J2000.0)
29 A1 --- DE- Declination sign (J2000.0)
30- 31 I2 deg DEd Declination (J2000.0)
33- 34 I2 arcmin DEm Declination (J2000.0)
36- 37 I2 arcsec DEs Declination (J2000.0)
40- 43 F4.2 arcmin R Radius
46- 49 F4.2 mag E(V-I) Foreground reddening
52- 55 F4.2 [yr] logAge cluster age in logarithmic scale
59 A1 --- l_logAgeG10 Limit flag on logAgeG10
60- 63 F4.2 [yr] logAgeG10 ?=- Earlier estimation of age by Glatt et al.
2010, Cat. J/A+A/517/50 (2)
67 A1 --- l_logAgePU99 Limit flag on loglogAgeG10
68- 70 F3.1 [yr] logAgePU99 ?=- Earlier estimation of age by Pietrzynski
& Udalski 1999AcA....49..157P 1999AcA....49..157P
74- 76 F3.1 [yr] logAgeC06 ?=- Earlier estimation of age by Chiosi et
al., 2006, Cat. J/A+A/452/179
79- 81 A3 --- Group Group number of cluster based on its strength
and mass range. (see Table 1 in the paper)
--------------------------------------------------------------------------------
Note (1): asterisk imply newly parametrised clusters.
Note (2): Blank space implies that cluster's age is not estimated by earlier
studies.
--------------------------------------------------------------------------------
Acknowledgements:
We thank the OGLE team for making the data available in public domain.
From Prasanta Kumar Nayak, prasanta(at)iiap.res.in
References:
Nayak et al., Paper I 2016MNRAS.463.1446N 2016MNRAS.463.1446N, Cat. J/MNRAS/463/1446
(End) Patricia Vannier [CDS] 15-Jul-2018