J/MNRAS/473/105  LMC Washington CMT1 photometry of star clusters (Piatti+, 2018)
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Star cluster formation history along the minor axis of the
Large Magellanic Cloud.
    Piatti A.E., Cole A.A., Emptage B.
   <Mon. Not. R. Astron. Soc., 473, 105-115 (2018)>
   =2018MNRAS.473..105P    (SIMBAD/NED BibCode)
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ADC_Keywords: Magellanic Clouds ; Associations, stellar ; Photometry, CMT1T2V
Keywords: techniques: photometric - galaxies: individual: LMC -
          galaxies: star clusters: general

Abstract:
    We analysed Washington CMT1 photometry of star clusters located along
    the minor axis of the Large Magellanic Cloud (LMC), from the LMC
    optical centre up to ~39{deg} outwards to the North-West. The data
    base was exploited in order to search for new star cluster candidates,
    to produce cluster CMDs cleaned from field star contamination and to
    derive age estimates for a statistically complete cluster sample. We
    confirmed that 146 star cluster candidates are genuine physical
    systems, and concluded that an overall ~30 per cent of catalogued
    clusters in the surveyed regions are unlikely to be true physical
    systems. We did not find any new cluster candidates in the outskirts
    of the LMC (deprojected distance >~8{deg}). The derived ages of the
    studied clusters are in the range 7.2<log(t[yr^-1^])<=9.4, with the
    sole exception of the globular cluster NGC 1786
    (log(t[yr^-1^])=10.10). We also calculated the cluster frequency for
    each region, from which we confirmed previously proposed outside-in
    formation scenarios. In addition, we found that the outer LMC fields
    show a sudden episode of cluster formation (log(t[yr^-1^])~7.8-7.9)
    which continued until log(t[yr^-1^])~7.3 only in the outermost LMC
    region. We link these features to the first pericentre passage of the
    LMC to the Milky Way (MW), which could have triggered cluster
    formation due to ram pressure interaction between the LMC and MW halo.

Description:
    The data used in this work come from the Cerro-Tololo Inter-American
    Observatory (CTIO) programme 2008B-0296 (PI: Cole) that focused on
    surveying the most metal poor stars outside the MW. We downloaded from
    the National Optical Astronomy Observatory (NOAO) Science Data
    Management (SDM) Archives1 Washington CM and Kron-Cousins R images
    obtained with the Mosaic II imager, an array of 8Kx8K CCDs covering a
    36-arcminx36-arcmin field, attached to the 4m Blanco telescope.

    In this work, we analysed Washington CMT1 photometry of star clusters
    located along the minor axis of the LMC. We covered a wide baseline in
    deprojected distances, from the very optical LMC centre up to ~39{deg}
    outwards to the North-West.

File Summary:
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 FileName     Lrecl  Records   Explanations
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ReadMe           80        .   This file
table4.dat       66       75   Fundamental properties of the star cluster sample
clusters/*        .       75   Photometric catalogue of stars of each clusters
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Byte-by-byte Description of file: table4.dat
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   Bytes Format Units    Label     Explanations
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   1-  2  I2    ---      Field     Field number
   4- 16  A13   ---      Cluster   Cluster name
  18- 21  F4.2  mag      E(V-I)    Colour excess in V-I
  23- 27  F5.2  [yr-1]   log(t)TW  Age from this work
  29- 32  F4.2  [yr-1] e_log(t)TW  rms uncertainty on log(t)TW
  34- 38  F5.2  [yr-1]   log(t)L   ? Age from literature
  40- 43  F4.2  [yr-1] e_log(t)L   ? rms uncertainty on log(t)L
  45- 47  A3    ---    r_log(t)L   ? Reference for log(t)L (1)
  49- 66  A18   ---      FileName  Name of the table with photometry in
                                    subdirectory clusters
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Note (1): References as follows:
           1 = Piatti (2011MNRAS.418L..40P)
           2 = Glatt et al. (2010, Cat. J/A+A/517/A50)
           3 = Piatti (2012, Cat. J/A+A/540/A58)
           4 = Choudhury, Subramaniam & Piatti (2015AJ....149...52C)
           5 = Piatti (2014MNRAS.440.3091P)
           6 = Brocato et al. (1996MNRAS.282..614B)
           7 = Carretta et al. (2000ApJ...533..215C)
           8 = Piatti et al. (2009, Cat. J/A+A/501/585)
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Byte-by-byte Description of file: clusters/*
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   Bytes Format Units   Label     Explanations
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   2-  7  I6    ---     ID        ID number
  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)
  36- 43  F8.3  pix     Xpos      X position
  45- 52  F8.3  pix     Ypos      Y position
  55- 61  F7.4  mag     Cmag      ?=99.9999 C magnitude
  65- 70  F6.4  mag   e_Cmag      ?=9.9999 rms uncertainty on Cmag
  73- 79  F7.4  mag     Mmag      M magnitude
  83- 88  F6.4  mag   e_Mmag      rms uncertainty on Mmag
  91- 97  F7.4  mag     T1mag     T1 magnitude
 101-106  F6.4  mag   e_T1mag     rms uncertainty on T1mag
 109-115  F7.4  ---     chi2      chi^2^ value
 117-124  F8.4  ---     Sharp     Sharpness
     128  I1    ---     Memb      [1/4] Membership (1)
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Note (1): Membership code as follows:
           1 = 25%
           2 = 50%
           3 = 75%
           4 = 100&
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History:
    From electronic version of the journal

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(End)                                      Patricia Vannier [CDS]    31-Jul-2020