The VMC Survey - XXI. New star cluster candidates discovered from infrared photometry in the Small Magellanic Cloud

A.E. Piatti, V.D. Ivanov, S. Rubele, M. Marconi, V. Ripepi, M.R.L. Cioni, J.M. Oliveira, Kenji Bekki

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    Abstract

    © 2016 The Authors. Published by Oxford University Press on behalf of The Royal Astronomical Society.We report the first search for new star clusters performed using the VISTA near-infrared YJKs Magellanic Clouds survey (VMC) data sets. We chose a pilot field of ~0.4 deg2 located in the South-west of the Small Magelllanic Cloud bar, where the star field is among the densest and highest reddened region in the galaxy. In order to devise an appropriate automatic procedure we made use of dimensions and stellar densities observed in the VMC data sets of the known clusters in this area. We executed different kernel density estimations over a sample of more than 358 000 stars with magnitudes measured in the three YJKs filters. We analysed the new cluster candidates whose colour-magnitude diagrams (CMDs), cleaned from field star contamination, were used to assess the clusters' reality and estimate reddenings and ages of the genuine systems. As a result 38 objects (≈ a 55 per cent increase in the known star clusters located in the surveyed field) of 0.15-0.40 arcmin (2.6-7.0 pc) in radius resulted to have near-infrared CMD features which resemble those of star clusters of young to moderate intermediate age (log(t yr-1) ~7.5-9.0). Most of the new star cluster candidates are hardly recognizable in optical images without the help of a sound star field decontaminated CMD analysis. For highly reddened star cluster candidates (E(B-V) ≥ 0.6 mag) the VMC data sets were necessary in order to recognize them.
    Original languageEnglish
    Pages (from-to)383-395
    JournalMonthly Notices of the Royal Astronomical Society
    Volume460
    Issue number1
    DOIs
    Publication statusPublished - 2016

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    infrared photometry
    star clusters
    Magellanic clouds
    star distribution
    color-magnitude diagram
    diagram
    near infrared
    filter
    contamination
    galaxies
    filters
    stars
    radii
    acoustics
    estimates

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    Piatti, A.E. ; Ivanov, V.D. ; Rubele, S. ; Marconi, M. ; Ripepi, V. ; Cioni, M.R.L. ; Oliveira, J.M. ; Bekki, Kenji. / The VMC Survey - XXI. New star cluster candidates discovered from infrared photometry in the Small Magellanic Cloud. In: Monthly Notices of the Royal Astronomical Society. 2016 ; Vol. 460, No. 1. pp. 383-395.
    @article{571e342bb112471c8c7eef229f169181,
    title = "The VMC Survey - XXI. New star cluster candidates discovered from infrared photometry in the Small Magellanic Cloud",
    abstract = "{\circledC} 2016 The Authors. Published by Oxford University Press on behalf of The Royal Astronomical Society.We report the first search for new star clusters performed using the VISTA near-infrared YJKs Magellanic Clouds survey (VMC) data sets. We chose a pilot field of ~0.4 deg2 located in the South-west of the Small Magelllanic Cloud bar, where the star field is among the densest and highest reddened region in the galaxy. In order to devise an appropriate automatic procedure we made use of dimensions and stellar densities observed in the VMC data sets of the known clusters in this area. We executed different kernel density estimations over a sample of more than 358 000 stars with magnitudes measured in the three YJKs filters. We analysed the new cluster candidates whose colour-magnitude diagrams (CMDs), cleaned from field star contamination, were used to assess the clusters' reality and estimate reddenings and ages of the genuine systems. As a result 38 objects (≈ a 55 per cent increase in the known star clusters located in the surveyed field) of 0.15-0.40 arcmin (2.6-7.0 pc) in radius resulted to have near-infrared CMD features which resemble those of star clusters of young to moderate intermediate age (log(t yr-1) ~7.5-9.0). Most of the new star cluster candidates are hardly recognizable in optical images without the help of a sound star field decontaminated CMD analysis. For highly reddened star cluster candidates (E(B-V) ≥ 0.6 mag) the VMC data sets were necessary in order to recognize them.",
    author = "A.E. Piatti and V.D. Ivanov and S. Rubele and M. Marconi and V. Ripepi and M.R.L. Cioni and J.M. Oliveira and Kenji Bekki",
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    The VMC Survey - XXI. New star cluster candidates discovered from infrared photometry in the Small Magellanic Cloud. / Piatti, A.E.; Ivanov, V.D.; Rubele, S.; Marconi, M.; Ripepi, V.; Cioni, M.R.L.; Oliveira, J.M.; Bekki, Kenji.

    In: Monthly Notices of the Royal Astronomical Society, Vol. 460, No. 1, 2016, p. 383-395.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - The VMC Survey - XXI. New star cluster candidates discovered from infrared photometry in the Small Magellanic Cloud

    AU - Piatti, A.E.

    AU - Ivanov, V.D.

    AU - Rubele, S.

    AU - Marconi, M.

    AU - Ripepi, V.

    AU - Cioni, M.R.L.

    AU - Oliveira, J.M.

    AU - Bekki, Kenji

    PY - 2016

    Y1 - 2016

    N2 - © 2016 The Authors. Published by Oxford University Press on behalf of The Royal Astronomical Society.We report the first search for new star clusters performed using the VISTA near-infrared YJKs Magellanic Clouds survey (VMC) data sets. We chose a pilot field of ~0.4 deg2 located in the South-west of the Small Magelllanic Cloud bar, where the star field is among the densest and highest reddened region in the galaxy. In order to devise an appropriate automatic procedure we made use of dimensions and stellar densities observed in the VMC data sets of the known clusters in this area. We executed different kernel density estimations over a sample of more than 358 000 stars with magnitudes measured in the three YJKs filters. We analysed the new cluster candidates whose colour-magnitude diagrams (CMDs), cleaned from field star contamination, were used to assess the clusters' reality and estimate reddenings and ages of the genuine systems. As a result 38 objects (≈ a 55 per cent increase in the known star clusters located in the surveyed field) of 0.15-0.40 arcmin (2.6-7.0 pc) in radius resulted to have near-infrared CMD features which resemble those of star clusters of young to moderate intermediate age (log(t yr-1) ~7.5-9.0). Most of the new star cluster candidates are hardly recognizable in optical images without the help of a sound star field decontaminated CMD analysis. For highly reddened star cluster candidates (E(B-V) ≥ 0.6 mag) the VMC data sets were necessary in order to recognize them.

    AB - © 2016 The Authors. Published by Oxford University Press on behalf of The Royal Astronomical Society.We report the first search for new star clusters performed using the VISTA near-infrared YJKs Magellanic Clouds survey (VMC) data sets. We chose a pilot field of ~0.4 deg2 located in the South-west of the Small Magelllanic Cloud bar, where the star field is among the densest and highest reddened region in the galaxy. In order to devise an appropriate automatic procedure we made use of dimensions and stellar densities observed in the VMC data sets of the known clusters in this area. We executed different kernel density estimations over a sample of more than 358 000 stars with magnitudes measured in the three YJKs filters. We analysed the new cluster candidates whose colour-magnitude diagrams (CMDs), cleaned from field star contamination, were used to assess the clusters' reality and estimate reddenings and ages of the genuine systems. As a result 38 objects (≈ a 55 per cent increase in the known star clusters located in the surveyed field) of 0.15-0.40 arcmin (2.6-7.0 pc) in radius resulted to have near-infrared CMD features which resemble those of star clusters of young to moderate intermediate age (log(t yr-1) ~7.5-9.0). Most of the new star cluster candidates are hardly recognizable in optical images without the help of a sound star field decontaminated CMD analysis. For highly reddened star cluster candidates (E(B-V) ≥ 0.6 mag) the VMC data sets were necessary in order to recognize them.

    U2 - 10.1093/mnras/stw1000

    DO - 10.1093/mnras/stw1000

    M3 - Article

    VL - 460

    SP - 383

    EP - 395

    JO - Monthly Notices of the Royal Astronomical Society

    JF - Monthly Notices of the Royal Astronomical Society

    SN - 0035-8711

    IS - 1

    ER -