Formation and evolution of the local interstellar environment: combined constraints from nucleosynthetic and X-ray data
Formation and evolution of the local interstellar environment: combined constraints from nucleosynthetic and X-ray data
复制标题
DOI：
10.1093/mnras/staa2778
复制
发表时间：
2020-07
影响因子：
4.8
通讯作者：
Y. Fujimoto;M. Krumholz;S. Inutsuka;A. Boss;L. Nittler
中科院分区：
文献类型：
--
作者：
Y. Fujimoto;M. Krumholz;S. Inutsuka;A. Boss;L. Nittler
几个观测结果表明，太阳系位于一个受到大质量恒星反馈影响的区域至少有几百万年;这些观测结果包括在深海档案和南极雪中探测到的活性$^{60}\text{Fe}$，在全天伽马射线地图中看到的银河平面周围的广泛角分布$^{26}\text{Al}$，以及全天软X射线背景。然而，我们在银河系圆盘内的位置使我们很难完全了解这个环境，而且我们有限的时间基线无法提供有关其形成历史或与大规模银河系动力学关系的信息。我们探索这些问题，通过使用一个$N$-体+流体动力学模拟的银河系，以确定恒星的太阳一样的轨道，其环境将产生与我们观察到的条件一致。我们发现这样的恒星并不常见，但也不是特别罕见。这些恒星主要位于旋臂的边缘附近，并位于kpc尺度的气泡内，这些气泡是由旋臂中多代星星形成而产生的。我们研究了恒星的轨迹，发现它们在气泡中停留的时间从2000万年到9000万年不等。持续时间取决于恒星穿过旋臂的时间，这通常比气泡的寿命短，由于旋臂环境提供了持续的气体供应，气泡的寿命为1亿年。
Several observations suggest that the Solar system has been located in a region affected by massive stellar feedback for at least a few Myr; these include detection of live $^{60}\text{Fe}$ in deep-sea archives and Antarctic snow, the broad angular distribution of $^{26}\text{Al}$ around the Galactic plane seen in all-sky $\gamma$-ray maps, and the all-sky soft X-ray background. However, our position inside the Galactic disc makes it difficult to fully characterise this environment, and our limited time baseline provides no information about its formation history or relation to large-scale Galactic dynamics. We explore these questions by using an $N$-body+hydrodynamics simulation of a Milky-Way-like galaxy to identify stars on Sun-like orbits whose environments would produce conditions consistent with those we observe. We find that such stars are uncommon but not exceptionally rare. These stars are found predominantly near the edges of spiral arms, and lie inside kpc-scale bubbles that are created by multiple generations of star formation in the arm. We investigate the stars' trajectories and find that the duration of the stay in the bubble ranges from 20 Myr to 90 Myr. The duration is governed by the crossing time of stars across the spiral arm. This is generally shorter than the bubble lifetime, which is $\sim 100$ Myr as a result of the continuous gas supply provided by the arm environment.