Discovery of extended main-sequence turnoffs in four young massive clusters in the Magellanic Clouds

Chengyuan Li; Richard de Grijs; Licai Deng; Antonino P. Milone

doi:10.3847/1538-4357/aa7b36

Discovery of extended main-sequence turnoffs in four young massive clusters in the Magellanic Clouds

Chengyuan Li^*, Richard de Grijs, Licai Deng, Antonino P. Milone

^*Corresponding author for this work

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

44 Citations (Scopus)

67 Downloads (Pure)

Abstract

An increasing number of young massive clusters (YMCs) in the Magellanic Clouds have been found to exhibit bimodal or extended main sequences (MSs) in their color-magnitude diagrams (CMDs). These features are usually interpreted in terms of a coeval stellar population with different stellar rotational rates, where the blue and red MS stars are populated by non- (or slowly) and rapidly rotating stellar populations, respectively. However, some studies have shown that an age spread of several million years is required to reproduce the observed wide turnoff regions in some YMCs. Here we present the ultraviolet-visual CMDs of four Large and Small Magellanic Cloud YMCs, NGC 330, NGC 1805, NGC 1818, and NGC 2164, based on high-precision Hubble Space Telescope photometry. We show that they all exhibit extended main-sequence turnoffs (MSTOs). The importance of age spreads and stellar rotation in reproducing the observations is investigated. The observed extended MSTOs cannot be explained by stellar rotation alone. Adopting an age spread of 35-50 Myr can alleviate this difficulty. We conclude that stars in these clusters are characterized by ranges in both their ages and rotation properties, but the origin of the age spread in these clusters remains unknown.

Original language	English
Article number	119
Pages (from-to)	1-12
Number of pages	12
Journal	The Astrophysical Journal: an international review of astronomy and astronomical physics
Volume	844
Issue number	2
DOIs	https://doi.org/10.3847/1538-4357/aa7b36
Publication status	Published - 1 Aug 2017

Bibliographical note

Copyright 2017 The American Astronomical Society. First published in the Astrophysical journal, 844(2), 119, 2017, published by IOP Publishing. The original publication is available at http://www.doi.org/10.3847/1538-4357/aa7b36. 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.

Keywords

globular clusters: individual (NGC 330, NGC 1805, NGC 1818, NGC 2164)
Hertzsprung-Russell and C-M diagrams
Magellanic Clouds
globular clusters: Individual (NGC 330, NGC 1805, NGC 1818, NGC 2164)

Access to Document

10.3847/1538-4357/aa7b36

Publisher version (open access)Final published version, 3.13 MBLicence: Unspecified

Cite this

@article{3a99c5ba355a415d81fbad125549c9c0,

title = "Discovery of extended main-sequence turnoffs in four young massive clusters in the Magellanic Clouds",

abstract = "An increasing number of young massive clusters (YMCs) in the Magellanic Clouds have been found to exhibit bimodal or extended main sequences (MSs) in their color-magnitude diagrams (CMDs). These features are usually interpreted in terms of a coeval stellar population with different stellar rotational rates, where the blue and red MS stars are populated by non- (or slowly) and rapidly rotating stellar populations, respectively. However, some studies have shown that an age spread of several million years is required to reproduce the observed wide turnoff regions in some YMCs. Here we present the ultraviolet-visual CMDs of four Large and Small Magellanic Cloud YMCs, NGC 330, NGC 1805, NGC 1818, and NGC 2164, based on high-precision Hubble Space Telescope photometry. We show that they all exhibit extended main-sequence turnoffs (MSTOs). The importance of age spreads and stellar rotation in reproducing the observations is investigated. The observed extended MSTOs cannot be explained by stellar rotation alone. Adopting an age spread of 35-50 Myr can alleviate this difficulty. We conclude that stars in these clusters are characterized by ranges in both their ages and rotation properties, but the origin of the age spread in these clusters remains unknown.",

keywords = "globular clusters: individual (NGC 330, NGC 1805, NGC 1818, NGC 2164), Hertzsprung-Russell and C-M diagrams, Magellanic Clouds, globular clusters: Individual (NGC 330, NGC 1805, NGC 1818, NGC 2164)",

author = "Chengyuan Li and {de Grijs}, Richard and Licai Deng and Milone, {Antonino P.}",

note = "Copyright 2017 The American Astronomical Society. First published in the Astrophysical journal, 844(2), 119, 2017, published by IOP Publishing. The original publication is available at http://www.doi.org/10.3847/1538-4357/aa7b36. 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.",

year = "2017",

month = aug,

day = "1",

doi = "10.3847/1538-4357/aa7b36",

language = "English",

volume = "844",

pages = "1--12",

journal = "The Astrophysical Journal: an international review of astronomy and astronomical physics",

issn = "0004-637X",

publisher = "IOP Publishing",

number = "2",

}

TY - JOUR

T1 - Discovery of extended main-sequence turnoffs in four young massive clusters in the Magellanic Clouds

AU - Li, Chengyuan

AU - de Grijs, Richard

AU - Deng, Licai

AU - Milone, Antonino P.

N1 - Copyright 2017 The American Astronomical Society. First published in the Astrophysical journal, 844(2), 119, 2017, published by IOP Publishing. The original publication is available at http://www.doi.org/10.3847/1538-4357/aa7b36. 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.

PY - 2017/8/1

Y1 - 2017/8/1

N2 - An increasing number of young massive clusters (YMCs) in the Magellanic Clouds have been found to exhibit bimodal or extended main sequences (MSs) in their color-magnitude diagrams (CMDs). These features are usually interpreted in terms of a coeval stellar population with different stellar rotational rates, where the blue and red MS stars are populated by non- (or slowly) and rapidly rotating stellar populations, respectively. However, some studies have shown that an age spread of several million years is required to reproduce the observed wide turnoff regions in some YMCs. Here we present the ultraviolet-visual CMDs of four Large and Small Magellanic Cloud YMCs, NGC 330, NGC 1805, NGC 1818, and NGC 2164, based on high-precision Hubble Space Telescope photometry. We show that they all exhibit extended main-sequence turnoffs (MSTOs). The importance of age spreads and stellar rotation in reproducing the observations is investigated. The observed extended MSTOs cannot be explained by stellar rotation alone. Adopting an age spread of 35-50 Myr can alleviate this difficulty. We conclude that stars in these clusters are characterized by ranges in both their ages and rotation properties, but the origin of the age spread in these clusters remains unknown.

AB - An increasing number of young massive clusters (YMCs) in the Magellanic Clouds have been found to exhibit bimodal or extended main sequences (MSs) in their color-magnitude diagrams (CMDs). These features are usually interpreted in terms of a coeval stellar population with different stellar rotational rates, where the blue and red MS stars are populated by non- (or slowly) and rapidly rotating stellar populations, respectively. However, some studies have shown that an age spread of several million years is required to reproduce the observed wide turnoff regions in some YMCs. Here we present the ultraviolet-visual CMDs of four Large and Small Magellanic Cloud YMCs, NGC 330, NGC 1805, NGC 1818, and NGC 2164, based on high-precision Hubble Space Telescope photometry. We show that they all exhibit extended main-sequence turnoffs (MSTOs). The importance of age spreads and stellar rotation in reproducing the observations is investigated. The observed extended MSTOs cannot be explained by stellar rotation alone. Adopting an age spread of 35-50 Myr can alleviate this difficulty. We conclude that stars in these clusters are characterized by ranges in both their ages and rotation properties, but the origin of the age spread in these clusters remains unknown.

KW - globular clusters: individual (NGC 330, NGC 1805, NGC 1818, NGC 2164)

KW - Hertzsprung-Russell and C-M diagrams

KW - Magellanic Clouds

KW - globular clusters: Individual (NGC 330, NGC 1805, NGC 1818, NGC 2164)

UR - http://www.scopus.com/inward/record.url?scp=85049201327&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/aa7b36

DO - 10.3847/1538-4357/aa7b36

M3 - Article

SN - 0004-637X

VL - 844

SP - 1

EP - 12

JO - The Astrophysical Journal: an international review of astronomy and astronomical physics

JF - The Astrophysical Journal: an international review of astronomy and astronomical physics

IS - 2

M1 - 119

ER -

Discovery of extended main-sequence turnoffs in four young massive clusters in the Magellanic Clouds

Abstract

Bibliographical note

Keywords

Access to Document

Other files and links

Fingerprint

Cite this