J/A+A/606/A21 LMC bar star clusters (Piatti, 2017)
The real population of star clusters in the bar of the Large Magellanic Cloud.
Piatti A.E.
<Astron. Astrophys. 606, A21 (2017)>
=2017A&A...606A..21P 2017A&A...606A..21P (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Associations, stellar ; Photometry, CMT1T2V
Keywords: techniques: photometric - galaxies: individual: LMC -
Magellanic Clouds
Abstract:
We report results on star clusters located in the South-Eastern half
of the Large Magellanic (LMC) bar fromWashington CT1 photometry. Using
appropriate kernel density estimators we detected 73 star cluster
candidates, three of which do not show any detectable trace of star
cluster sequences in their colour-magnitude diagrams (CMDs).We did not
detect other 38 previously catalogued clusters, which could not be
recognized when visually inspecting the C and T1 images either; the
distribution of stars in their respective fields do not resemble that
of an stellar aggregate. They represent ∼33 per cent of all catalogued
objects located within the analysed LMC bar field. From matching
theoretical isochrones to the cluster CMDs cleaned from field star
contamination, we derived ages in the range 7.2<log(t[yr-1])<10.1.
As far as we are aware, this is the first time homogeneous age
estimates based on resolved stellar photometry are obtained for most
of the studied clusters. We built the cluster frequency (CF) for the
surveyed area, and found that the major star cluster formation
activity has taken place during the period log(t[yr-1])∼8.0-9.0.
Since ∼100Myr ago, clusters have been formed during few bursting
formation episodes. When comparing the observed CF to that recovered
from the star formation rate we found noticeable differences, which
suggests that field star and star cluster formation histories could
have been significantly different.
Description:
Magnitudes and colours of stars in the field of 70 clusters whose name
are used as rootname of each file (e.g. ngc1969.dat corresponds to
data for NGC 1969).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 55 70 Fundamental properties of the star cluster sample
clusters.dat 82 83013 Magnitudes and colours of stars of the 70 clusters
files/* . 70 Individual cluster magnitudes and colours of stars
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Cluster name
15- 18 F4.2 mag E(V-I) V-I colour excess
19 A1 --- n_E(V-I) [)] Note on E(V-I) (1)
21- 25 F5.2 [yr-1] logt Age
27- 30 I4 --- Nstar Number of stars in the cluster
32- 40 A9 --- Cluster Cluster shorted name (as in clusters.dat file)
44- 55 A12 --- FileName Name of the individual cluster file in
subdirectory files
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Note (1): ) indicates E(V-I) values slightly larger than those from Haschke et
al. (2011AJ....141..158H 2011AJ....141..158H) to get a better isochrone matching.
Nevertheless they are within the dispersion given for the OGLE III E(V-I)
colour excesses.
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Byte-by-byte Description of file: clusters.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Cluster Cluster shorted name
11- 15 I5 --- ID Star number within the cluster
18- 19 I2 h RAh Right ascension (J2000)
21- 22 I2 min RAm Right ascension (J2000)
24- 29 F6.3 s RAs Right ascension (J2000)
31 A1 --- DE- Declination sign (J2000)
32- 33 I2 deg DEd Declination (J2000)
35- 36 I2 arcmin DEm Declination (J2000)
38- 42 F5.2 arcsec DEs Declination (J2000)
45- 51 F7.4 mag Cmag ?=99.9999 C magnitude
55- 60 F6.4 mag e_Cmag ?=9.9999 rms uncertainty on Cmag
63- 69 F7.4 mag T1mag ?=99.9999 T1 magnitude
73- 78 F6.4 mag e_T1mag ?=9.9999 rms uncertainty on T1mag
82 I1 --- Memb [1/4] Membership probability code (G1)
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Byte-by-byte Description of file: files/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 I7 --- ID Star number within the cluster
10- 11 I2 h RAh Right ascension (J2000)
12 A1 --- --- [:]
13- 14 I2 min RAm Right ascension (J2000)
15 A1 --- --- [:]
16- 21 F6.3 s RAs Right ascension (J2000)
23 A1 --- DE- Declination sign (J2000)
24- 25 I2 deg DEd Declination (J2000)
26 A1 --- --- [:]
27- 28 I2 arcmin DEm Declination (J2000)
29 A1 --- --- [:]
30- 34 F5.2 arcsec DEs Declination (J2000)
37- 43 F7.4 mag Cmag ?=99.9999 C magnitude
47- 52 F6.4 mag e_Cmag ?=9.9999 rms uncertainty on Cmag
55- 61 F7.4 mag T1mag ?=99.9999 T1 magnitude
65- 70 F6.4 mag e_T1mag ?=9.9999 rms uncertainty on T1mag
74 I1 --- Memb [1/4] Membership probability code (G1)
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Global notes:
Note (G1): Membership probability code as follows:
1 = 25%
2 = 50%
3 = 75%
4 = 100%
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Acknowledgements:
Andres Piatti, andres(at)oac.unc.edu.ar
(End) Patricia Vannier [CDS] 25-Jul-2017