arXiv 1709.010792017-09astro-ph.GA

老的富金属疏散星团NGC 6791起源和演化的新认识

New insights in the origin and evolution of the old, metal-rich open cluster NGC 6791

Luis A. Martinez-Medina, Mark Gieles, Barbara Pichardo, Antonio Peimbert

备注：: 14 pages, 10 Figures, 3 Tables. Accepted for publication in MNRAS
DOI：: 10.1093/mnras/stx2739

摘要：

NGC 6791是研究最多的疏散星团之一，它是巨大的（$\sim5000\,M_{\odot}$），位于太阳圈，古老的（$~8\,$ Gyr），但也是银河系中已知的最富金属的星团（${\rm [Fe/H]}\simeq0.4$）。通过在包括旋臂和棒的银河系模型中进行轨道分析，我们发现NGC 6791可能形成于内部薄盘或凸起中，后来通过径向迁移转移到当前轨道。我们应用不同的工具来模拟NGC 6791，包括直接$N$体求和的时变电位，以测试其生存能力时，通过不同的银河系环境。为了在8 Gyr的迁移轨道上生存下来，NGC 6791在形成时必须有更大的质量，$M_0 \geq 5\times10^4 M_{\odot}$。我们在恒星质量函数中发现了这个初始质量的独立确认，它被观察到是平坦的;这只能解释为星团所经历的平均潮汐场强度比它在当前轨道上的强度更强。因此，NGC 6791的诞生地和旅程都在其化学成分、质量损失和平坦的恒星质量函数中留下了印记，支持它起源于内部薄盘或凸起。

英文摘要：

NGC 6791 is one of the most studied open clusters, it is massive ($\sim5000\,M_{\odot}$), located at the solar circle, old ($~8\,$Gyr) and yet the most metal-rich cluster (${\rm [Fe/H]}\simeq0.4$) known in the Milky Way. By performing an orbital analysis within a Galactic model including spiral arms and a bar, we found that it is plausible that NGC 6791 formed in the inner thin disc or in the bulge, and later displaced by radial migration to its current orbit. We apply different tools to simulate NGC 6791, including direct $N$-body summation in time-varying potentials, to test its survivability when going through different Galactic environments. In order to survive the 8 Gyr journey moving on a migrating orbit, NGC 6791 must have been more massive, $M_0 \geq 5\times10^4 M_{\odot}$, when formed. We find independent confirmation of this initial mass in the stellar mass function, which is observed to be flat; this can only be explained if the average tidal field strength experienced by the cluster is stronger than what it is at its current orbit. Therefore, the birth place and journeys of NGC 6791 are imprinted in its chemical composition, in its mass loss, and in its flat stellar mass function, supporting its origin in the inner thin disc or in the bulge.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

摘要：

英文摘要：

相关论文