Free Access
Volume 581, September 2015
Article Number A111
Number of page(s) 13
Section Galactic structure, stellar clusters and populations
Published online 16 September 2015

Online material

thumbnail Fig. 2

Top row: black circles show the comparison of the aperture photometry of stars derived in this work versus the PSC values, and red circles are the comparison of our aperture photometry of the star clusters versus the PSC values for the 109 clusters for which the PSC has aperture photometry. Central row: black squares show the photometric uncertainties provided by the PSC for 109 clusters and all circles show the photometric uncertainties derived for our aperture photometry for 758 clusters. The red circles are 502 clusters with uncertainties lower than the limit of 0.3 mag (dashed line) in all JHK passbands, and the open circles are the clusters for which the photometry does not satisfy this criteria. Bottom row: distributions of cluster brightness: white histograms contain the 758 clusters for which we derived photometry and the gray ones contain the 502 clusters that satisfy the photometric uncertainty criteria. The thick open histograms represent the 109 clusters contained in the PSC, for comparison. In each row, the situation is shown for J (left panels), H (central panels), and K (right panels) passbands.

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thumbnail Fig. 5

Artificial tests for 10 000 clusters with true age and metallicity following a defined age-metallicity relation (see text), and with a true mass fixed to log 10(M/M) = 4. The first column of panels displays the age derived vs. the true age, the second column shows the derived mass distribution, the third column shows the true age distribution (solid line histogram) and derived age distribution (dashed line histogram), and the last column shows the differential true age distribution (solid line), which is composed of a two-slope profile, and the derived differential age distribution (dashed line). The first row of panels shows results obtained using the UBVRI photometric system, the second row shows the results obtained using the UBVRI + JHK system and the last row shows the results obtained with the GALEX + UBVRI system. Here the metallicity of the model grid is fixed to [ M / H ] = −0.4.

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thumbnail Fig. 6

Same as in Fig. 5, but here, for clusters which have derived ages larger than log 10(t/ yr) = 9 when using fixed [ M/H ] = −0.4 metallicity, we re-derive a solution leaving the metallicity free to vary in the range [+0.2, −2.2 ].

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thumbnail Fig. 7

Same as in Fig. 5, but here the metallicity of the model grid is left free over the whole age range.

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thumbnail Fig. 8

Comparison of the age and mass derived for clusters common with San Roman et al. (2009) (panels a), b), e), f)), and for clusters common with Sarajedini & Mancone (2007) (panels c), d), g), h)). First row: comparison of the parameters of these studies vs. this work; second row: difference of the parameters derived in their studies and this work vs. the parameters derived in this work. The color-coding of clusters is the same as defined in Fig. 3.

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© ESO, 2015

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