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http://hdl.handle.net/20.500.12386/30438
Titolo: | The Peculiar Radial Distribution of Multiple Populations in the Massive Globular Cluster M80 | Autori: | Dalessandro, Emanuele Cadelano, M. Vesperini, E. Salaris, M. Ferraro, F. R. Lanzoni, B. Raso, S. Hong, J. Webb, J. J. Zocchi, A. |
Data pubblicazione: | 2018 | Rivista: | THE ASTROPHYSICAL JOURNAL | Numero: | 859 | Fascicolo: | 1 | Da pagina:: | 15 | Abstract: | We present a detailed analysis of the radial distribution of light-element multiple populations (LE-MPs) in the massive and dense globular cluster M80, based on a combination of UV and optical Hubble Space Telescope data. Surprisingly, we find that first-generation (FG) stars (FG) are significantly more centrally concentrated than extreme second-generation (SG) stars out to ˜2.5r h from the cluster center. To understand the origin of such peculiar behavior, we used a set of N-body simulations following the long-term dynamical evolution of LE-MPs. We find that, given the advanced dynamical state of the cluster, the observed difference does not depend on the primordial relative distributions of FG and SG stars. On the contrary, a difference of ˜0.05-0.10 M ⊙ between the average masses of the two subpopulations is needed to account for the observed radial distributions. We argue that such a mass difference might be the result of the higher He abundance of SG stars (of the order of ΔY ˜ 0.05-0.06) with respect to FG stars. Interestingly, we find that a similar He variation is necessary to reproduce the horizontal branch morphology of M80. These results demonstrate that differences in mass among LE-MPs, due to different He content, should be properly taken into account for a correct interpretation of their radial distribution, at least in dynamically evolved systems. | URI: | http://hdl.handle.net/20.500.12386/30438 | URL: | https://iopscience.iop.org/article/10.3847/1538-4357/aabb56 | ISSN: | 0004-637X | DOI: | 10.3847/1538-4357/aabb56 | Bibcode ADS: | 2018ApJ...859...15D | Fulltext: | open |
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