The Spatial distributions of blue main-sequence stars in Magellanic Cloud star clusters

Yujiao Yang; Chengyuan Li; Richard de Grijs; Licai Deng

doi:10.3847/1538-4357/abec4b

The Spatial distributions of blue main-sequence stars in Magellanic Cloud star clusters

Yujiao Yang, Chengyuan Li, Richard de Grijs, Licai Deng

Centre in Astronomy, Astrophysics & Astrophotonics

Research output: Contribution to journal › Article › peer-review

2 Citations (Scopus)

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Abstract

The color–magnitude diagrams of young star clusters show that, particularly at ultraviolet wavelengths, their upper main sequences (MSs) bifurcate into a sequence comprising the bulk population and a blue periphery. The spatial distribution of stars is crucial to understanding the reasons for these distinct stellar populations. This study uses high-resolution photometric data obtained with the Hubble Space Telescope to study the spatial distributions of the stellar populations in seven Magellanic Cloud star clusters. The cumulative radial number fractions of blue stars within four clusters are strongly anticorrelated with those of the high mass ratio binaries in the bifurcated region, with negative Pearson coefficients <−0.7. Those clusters are generally young or in an early dynamical evolutionary stage. In addition, a supporting N-body simulation suggests that the increasing percentage of blue MS stars from the cluster centers to their outskirts may be associated with the dissolution of soft binaries. This study provides a different perspective to explore the MS bimodalities in young clusters and adds extra puzzles. A more comprehensive study combined with detailed simulations is needed in the future.

Original language	English
Article number	27
Pages (from-to)	1-15
Number of pages	15
Journal	Astronomical Journal
Volume	912
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/abec4b
Publication status	Published - 1 May 2021

Bibliographical note

Copyright © 2021 The American Astronomical Society. First published in the Astrophysical Journal, 912(1), 27, 2021, published by IOP Publishing. The original publication is available at https://doi.org/10.3847/1538-4357/abec4b. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

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title = "The Spatial distributions of blue main-sequence stars in Magellanic Cloud star clusters",

abstract = "The color–magnitude diagrams of young star clusters show that, particularly at ultraviolet wavelengths, their upper main sequences (MSs) bifurcate into a sequence comprising the bulk population and a blue periphery. The spatial distribution of stars is crucial to understanding the reasons for these distinct stellar populations. This study uses high-resolution photometric data obtained with the Hubble Space Telescope to study the spatial distributions of the stellar populations in seven Magellanic Cloud star clusters. The cumulative radial number fractions of blue stars within four clusters are strongly anticorrelated with those of the high mass ratio binaries in the bifurcated region, with negative Pearson coefficients <−0.7. Those clusters are generally young or in an early dynamical evolutionary stage. In addition, a supporting N-body simulation suggests that the increasing percentage of blue MS stars from the cluster centers to their outskirts may be associated with the dissolution of soft binaries. This study provides a different perspective to explore the MS bimodalities in young clusters and adds extra puzzles. A more comprehensive study combined with detailed simulations is needed in the future.",

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N2 - The color–magnitude diagrams of young star clusters show that, particularly at ultraviolet wavelengths, their upper main sequences (MSs) bifurcate into a sequence comprising the bulk population and a blue periphery. The spatial distribution of stars is crucial to understanding the reasons for these distinct stellar populations. This study uses high-resolution photometric data obtained with the Hubble Space Telescope to study the spatial distributions of the stellar populations in seven Magellanic Cloud star clusters. The cumulative radial number fractions of blue stars within four clusters are strongly anticorrelated with those of the high mass ratio binaries in the bifurcated region, with negative Pearson coefficients <−0.7. Those clusters are generally young or in an early dynamical evolutionary stage. In addition, a supporting N-body simulation suggests that the increasing percentage of blue MS stars from the cluster centers to their outskirts may be associated with the dissolution of soft binaries. This study provides a different perspective to explore the MS bimodalities in young clusters and adds extra puzzles. A more comprehensive study combined with detailed simulations is needed in the future.

AB - The color–magnitude diagrams of young star clusters show that, particularly at ultraviolet wavelengths, their upper main sequences (MSs) bifurcate into a sequence comprising the bulk population and a blue periphery. The spatial distribution of stars is crucial to understanding the reasons for these distinct stellar populations. This study uses high-resolution photometric data obtained with the Hubble Space Telescope to study the spatial distributions of the stellar populations in seven Magellanic Cloud star clusters. The cumulative radial number fractions of blue stars within four clusters are strongly anticorrelated with those of the high mass ratio binaries in the bifurcated region, with negative Pearson coefficients <−0.7. Those clusters are generally young or in an early dynamical evolutionary stage. In addition, a supporting N-body simulation suggests that the increasing percentage of blue MS stars from the cluster centers to their outskirts may be associated with the dissolution of soft binaries. This study provides a different perspective to explore the MS bimodalities in young clusters and adds extra puzzles. A more comprehensive study combined with detailed simulations is needed in the future.

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The Spatial distributions of blue main-sequence stars in Magellanic Cloud star clusters

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