Tidal-locking-induced Stellar Rotation Dichotomy in the Open Cluster NGC 2287?
Sun,Weijia1,2; Li,Chengyuan2,3; Deng,Licai2,4,5; de Grijs,Richard6,7,8
Source PublicationThe Astrophysical Journal
AbstractAbstract Stars spend most of their lifetimes on the “main sequence” (MS) in the Hertzsprung–Russell diagram. The obvious double MSs seen in the equivalent color–magnitude diagrams characteristic of Milky Way open clusters (OCs) pose a fundamental challenge to our traditional understanding of star clusters as “single stellar populations.” The clear MS bifurcation of early-type stars with masses greater than ~1.6 M⊙ is thought to result from a range in the stellar rotation rates. However, direct evidence connecting double MSs to stellar rotation properties has yet to emerge. Here, we show through analysis of the projected stellar rotational velocities (v sin i, where i represents the star’s inclination angle) that the well-separated double MS in the young, ~200 Myr old Milky Way OC NGC 2287 is tightly correlated with a dichotomous distribution of stellar rotation rates. We discuss whether our observations may reflect the effects of tidal locking affecting a fraction of the cluster’s member stars in stellar binary systems. We show that the slow rotators could potentially be initially rapidly rotating stars that have been slowed down by tidal locking by a low-mass-ratio companion in a cluster containing a large fraction of short-period, low-mass-ratio binaries. This demonstrates that stellar rotation drives the split MSs in young, ?300 Myr old star clusters. However, special conditions, e.g., as regards the mass-ratio distribution, might be required for this scenario to hold.
KeywordOpen star clusters Star clusters Stellar rotation
WOS IDIOP:0004-637X-883-2-ab3cd0
PublisherThe American Astronomical Society
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Document Type期刊论文
Affiliation1.Kavli Institute for Astronomy & Astrophysics and Department of Astronomy, Peking University, Yi He Yuan Lu 5, Hai Dian District, Beijing 100871, People’s Republic of China
2.Key Laboratory for Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012, People’s Republic of China
3.School of Physics and Astronomy, Sun Yat-sen University, Zhuhai 519082, People’s Republic of China
4.School of Astronomy and Space Science, University of the Chinese Academy of Sciences, Huairou 101408, People’s Republic of China
5.Department of Astronomy, China West Normal University, Nanchong 637002, People’s Republic of China
6.Department of Physics and Astronomy, Macquarie University, Balaclava Road, Sydney, NSW 2109, Australia
7.Research Centre for Astronomy, Astrophysics and Astrophotonics, Macquarie University, Balaclava Road, Sydney, NSW 2109, Australia
8.International Space Science Institute–Beijing, 1 Nanertiao, Hai Dian District, Beijing 100190, People’s Republic of China
First Author AffilicationNational Astronomical Observatories, Chinese Academy of Sciences
Recommended Citation
GB/T 7714
Sun,Weijia,Li,Chengyuan,Deng,Licai,et al. Tidal-locking-induced Stellar Rotation Dichotomy in the Open Cluster NGC 2287?[J]. The Astrophysical Journal,2019,883(2).
APA Sun,Weijia,Li,Chengyuan,Deng,Licai,&de Grijs,Richard.(2019).Tidal-locking-induced Stellar Rotation Dichotomy in the Open Cluster NGC 2287?.The Astrophysical Journal,883(2).
MLA Sun,Weijia,et al."Tidal-locking-induced Stellar Rotation Dichotomy in the Open Cluster NGC 2287?".The Astrophysical Journal 883.2(2019).
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