A discovery of young stellar objects in older clusters of the Large Magellanic Cloud

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Abstract

Recent studies have shown that an extended main-sequence turn-off is a common feature among intermediate-age clusters (1–3 Gyr) in the Magellanic Clouds. Multiple-generation star formation and stellar rotation or interacting binaries have been proposed to explain the feature. However, it remains controversial in the field of stellar populations. Here we present the main results of an ongoing star formation among older star clusters in the Large Magellanic Cloud. Cross-matching the positions of star clusters and young stellar objects has yielded 15 matches, with 7 located in the cluster centre. We demonstrate that this is not by chance by estimating local number densities of young stellar objects for each star cluster. This method is not based on isochrone fitting, which leads to some uncertainties in age estimation and methods of background subtraction. We also find no direct correlation between atomic hydrogen and the clusters. This suggests that gas accretion for fueling the star formation must be happening in situ. These findings support for the multiple-generations scenario as a plausible explanation for the extended main-sequence turn-off. © 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.
Original languageEnglish
Pages (from-to)L11-L15
Number of pages5
JournalMonthly Notices of the Royal Astronomical Society Letters
Volume468
Issue number1
Early online date2 Mar 2017
DOIs
Publication statusPublished - Jun 2017

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star clusters
Magellanic clouds
star formation
stellar rotation
refueling
accretion
hydrogen
subtraction
estimating
gas
gases
method
young
in situ

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title = "A discovery of young stellar objects in older clusters of the Large Magellanic Cloud",
abstract = "Recent studies have shown that an extended main-sequence turn-off is a common feature among intermediate-age clusters (1–3 Gyr) in the Magellanic Clouds. Multiple-generation star formation and stellar rotation or interacting binaries have been proposed to explain the feature. However, it remains controversial in the field of stellar populations. Here we present the main results of an ongoing star formation among older star clusters in the Large Magellanic Cloud. Cross-matching the positions of star clusters and young stellar objects has yielded 15 matches, with 7 located in the cluster centre. We demonstrate that this is not by chance by estimating local number densities of young stellar objects for each star cluster. This method is not based on isochrone fitting, which leads to some uncertainties in age estimation and methods of background subtraction. We also find no direct correlation between atomic hydrogen and the clusters. This suggests that gas accretion for fueling the star formation must be happening in situ. These findings support for the multiple-generations scenario as a plausible explanation for the extended main-sequence turn-off. {\circledC} 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.",
author = "Bi-Qing For and Kenji Bekki",
year = "2017",
month = "6",
doi = "10.1093/mnrasl/slx015",
language = "English",
volume = "468",
pages = "L11--L15",
journal = "Monthly Notices of the Royal Astronomical Society Letters",
issn = "1745-3925",
publisher = "Oxford University Press",
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}

TY - JOUR

T1 - A discovery of young stellar objects in older clusters of the Large Magellanic Cloud

AU - For, Bi-Qing

AU - Bekki, Kenji

PY - 2017/6

Y1 - 2017/6

N2 - Recent studies have shown that an extended main-sequence turn-off is a common feature among intermediate-age clusters (1–3 Gyr) in the Magellanic Clouds. Multiple-generation star formation and stellar rotation or interacting binaries have been proposed to explain the feature. However, it remains controversial in the field of stellar populations. Here we present the main results of an ongoing star formation among older star clusters in the Large Magellanic Cloud. Cross-matching the positions of star clusters and young stellar objects has yielded 15 matches, with 7 located in the cluster centre. We demonstrate that this is not by chance by estimating local number densities of young stellar objects for each star cluster. This method is not based on isochrone fitting, which leads to some uncertainties in age estimation and methods of background subtraction. We also find no direct correlation between atomic hydrogen and the clusters. This suggests that gas accretion for fueling the star formation must be happening in situ. These findings support for the multiple-generations scenario as a plausible explanation for the extended main-sequence turn-off. © 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.

AB - Recent studies have shown that an extended main-sequence turn-off is a common feature among intermediate-age clusters (1–3 Gyr) in the Magellanic Clouds. Multiple-generation star formation and stellar rotation or interacting binaries have been proposed to explain the feature. However, it remains controversial in the field of stellar populations. Here we present the main results of an ongoing star formation among older star clusters in the Large Magellanic Cloud. Cross-matching the positions of star clusters and young stellar objects has yielded 15 matches, with 7 located in the cluster centre. We demonstrate that this is not by chance by estimating local number densities of young stellar objects for each star cluster. This method is not based on isochrone fitting, which leads to some uncertainties in age estimation and methods of background subtraction. We also find no direct correlation between atomic hydrogen and the clusters. This suggests that gas accretion for fueling the star formation must be happening in situ. These findings support for the multiple-generations scenario as a plausible explanation for the extended main-sequence turn-off. © 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.

U2 - 10.1093/mnrasl/slx015

DO - 10.1093/mnrasl/slx015

M3 - Article

VL - 468

SP - L11-L15

JO - Monthly Notices of the Royal Astronomical Society Letters

JF - Monthly Notices of the Royal Astronomical Society Letters

SN - 1745-3925

IS - 1

ER -