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arXiv · 1804.03948

New insights into the formation of the blue main sequence in NGC 1850

Yujiao Yang·Chengyuan Li·Licai Deng·Richard de Grijs·Antonino P. Milone
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Abstract

Recent discoveries of bimodal main sequences (MSs) associated with young clusters (with ages $\lesssim 1$ Gyr) in the Magellanic Clouds have drawn a lot of attention. One of the prevailing formation scenarios attributes these split MSs to a bimodal distribution in stellar rotation rates, with most stars belonging to a rapidly rotating population. In this scenario, only a small fraction of stars populating a secondary blue sequence are slowly or non-rotating stars. Here, we focus on the blue MS in the young cluster NGC 1850. We compare the cumulative number fraction of the observed blue-MS stars to that of the high-mass-ratio binary systems at different radii. The cumulative distributions of both populations exhibit a clear anti-correlation, characterized by a highly significant Pearson coefficient of $-0.97$. Our observations are consistent with the possibility that blue-MS stars are low-mass-ratio binaries, and therefore their dynamical disruption is still ongoing. High-mass-ratio binaries, on the other hand, are more centrally concentrated.

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Yujiao Yang, Chengyuan Li, Licai Deng, Richard de Grijs, Antonino P. Milone. 2018-04-11. New insights into the formation of the blue main sequence in NGC 1850. https://doi.org/10.3847/1538-4357%2Faabe26

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