文章基本信息

标题：Blue Straggler Stars Beyond the Milky Way. III. Detection of Evolved Blue Straggler Candidates in Large Magellanic Cloud Clusters
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作者：Chengyuan Li ; Licai Deng ; Kenji Bekki 等
期刊名称：The Astronomical journal
印刷版ISSN：0004-6256
电子版ISSN：1538-3881
出版年度：2018
卷号：156
期号：3
页码：1-15
DOI：10.3847/1538-3881/aad463
语种：English
出版社：American Institute of Physics
摘要：We analyze Hubble Space Telescope observations of nine Large Magellanic Cloud star clusters with ages of1–2Gyr to search for evolved counterparts of blue straggler stars. Near the red clump regions in the clusters’ color–magnitude diagrams, we find branches of evolved stars that are much brighter than normal evolved stars. Weexamine the effects of photometric artifacts, differential reddening, and field contamination. We conclude thatthese bright evolved stars cannot be explained by any of these effects. Our statistical tests show that thecontributions of photometric uncertainties, crowding effects, and differential reddening to these bright evolvedstars are insufficient to fully explain their presence. Based on isochrone fitting, we have also ruled out thepossibility that these bright evolved stars could be reproduced by an internal chemical abundance spread. Thespatial distributions of the bright evolved stars exhibit clear concentrations that cannot be explained byhomogeneously distributed field stars. This is further confirmed based on Monte Carlo-based tests. By comparingour observations with stellar evolution models, we find that the masses of most of the bright evolved stars do notexceed twice the average mass of normal evolved stars. We suggest that these bright evolved stars are, in fact,evolved blue straggler stars.
关键词：blue stragglers;galaxies: star clusters;Hertzsprung–Russell and C–M diagrams;Magellanic Clouds