使明亮的巨人在银河系中心隐形
Making Bright Giants Invisible At The Galactic Centre
摘要：
目前对银河系中心（GC）的观测似乎显示出从$\sim 5"$向内明亮恒星的核心分布。另一方面，我们在GC观测到年轻的大质量恒星，其中大约20- 50%在一个圆盘中，大部分在明亮的巨星似乎缺乏的区域。在以前的出版物中，我们提出了这样的想法，即失踪的恒星与这个圆盘的存在有着深刻的联系。恒星盘的前身很可能是一个气体盘，在某个时候分裂并引发了恒星的形成。这导致了盘中出现高密度区域，这些区域的密度足够高，以确保剥离大型巨星的大气层，从而使它们非常微弱。在本文中，我们使用一个恒星演化代码来推导红巨星将显示在颜色星等图的属性，以及一个非线性因子所需的正确估计的质量损失。我们发现，在很短的时间尺度内，红巨星（RGs）离开了它们的标准演化轨道。非线性因子的值不仅取决于团块的性质，还取决于巨星的物理条件，正如我们通过分析预测的那样。根据我们的研究结果，包络剥离是有效的，在很短的时间尺度内将恒星从巨分支移动到白矮星阶段，从而使它们在观测中不可见。
英文摘要：
Current observations of the Galactic Center (GC) seem to display a core-like distribution of bright stars from $\sim 5"$ inwards. On the other hand, we observe young, massive stars at the GC, with roughly 20-50\% of them in a disc, mostly in the region where the bright giants appear to be lacking. In a previous publication we put the idea forward that the missing stars are deeply connected to the presence of this disc. The progenitor of the stellar disc is very likely to have been a gaseous disc that at some point fragmented and triggered star formation. This caused the appearance of overdensity regions in the disc that had high enough densities to ensure stripping large giants of their atmospheres and thus rendering them very faint. In this paper we use a stellar evolution code to derive the properties that a red giant would display in a colour-magnitude diagram, as well as a non-linearity factor required for a correct estimate of the mass loss. We find that in a very short timescale, the red giants (RGs) leave their standard evolutionary track. The non-linearity factor has values that not only depend on the properties of the clumps, but also on the physical conditions the giant stars, as we predicted analytically. According to our results, envelope stripping works, moving stars on a short timescale from the giant branch to the white dwarf stage, thus rendering them invisible to observations.
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