arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1704.03325astro-ph.GA
收藏

Gaia-ESO巡天:探索银河系隆起人口的复杂性质和起源

The Gaia-ESO Survey: Exploring the complex nature and origins of the Galactic bulge populations

A. Rojas-Arriagada, A. Recio-Blanco, P. de Laverny, Š. Mikolaitis, F. Matteucci, E. Spitoni, M. Schultheis, M. Hayden, V. Hill, M. Zoccali, D. Minniti, O. A. Go… 展开作者

A. Rojas-Arriagada, A. Recio-Blanco, P. de Laverny, Š. Mikolaitis, F. Matteucci, E. Spitoni, M. Schultheis, M. Hayden, V. Hill, M. Zoccali, D. Minniti, O. A. Gonzalez, G. Gilmore, S. Randich, S. Feltzing, E. J. Alfaro, C. Babusiaux, T. Bensby, A. Bragaglia, E. Flaccomio, S. E. Koposov, E. Pancino, A. Bayo, G. Carraro, A. R. Casey, M. T. Costado, F. Damiani, P. Donati, E. Franciosini, A. Hourihane, P. Jofré, C. Lardo, J. Lewis, K. Lind, L. Magrini, L. Morbidelli, G. G. Sacco, C. C. Worley, S. Zaggia

摘要:

摘要:我们使用Gaia-ESO调查的第四次内部数据发布来表征凸起的化学,空间分布,运动学,并将其与薄盘和厚盘进行化学比较。该样本由11个球区($-10^\circ\leq l\leq+8^\circ$和$-10^\circ\leq b\leq-4^\circ$)中的约2500颗红团星组成,以及一组约6300颗被选择用于比较的盘星。在整个采样区域,隆起区被证实是双峰的,在高纬度地区,贫金属恒星占主导地位。富含金属的恒星表现出棒状运动学,并在其星等分布中显示出双峰性,这一特征与X形凸起密切相关。它们在[Mg/Fe]与[Fe/H]平面上与薄盘序列的富金属端重叠。贫金属核球星具有更各向同性的热运动学,并且不参与X形核球。在相似的Mg增强水平下,在[Fe/H] $_{knee}=-0.37\pm0.09$处观察到贫金属凸起序列“膝”的位置,比厚盘的位置高0.06 dex。这表明,一个更高的SFR的隆起比厚盘。最后,我们提出了一个化学演化模型,适当地适合整个隆起序列,假设一个快速($<1$陀螺仪)在早期恒星形成的强烈爆发。我们将富含金属的恒星与早期薄盘长期演化形成的B/P凸起联系起来。另一方面,贫金属亚群可能是由大质量恒星主导的早期瞬时耗散坍缩的产物。尽管如此,我们的研究结果并不允许我们坚决排除这些恒星来自早期厚盘的长期演化的可能性。这是第一次在大面积的高分辨率、高S/N数据的均匀、全光谱分析的基础上,对隆凸区的δ和$α$ -丰度进行分析。

英文摘要:

Abridged: We used the fourth internal data release of the Gaia-ESO survey to characterize the bulge chemistry, spatial distribution, kinematics, and to compare it chemically with the thin and thick disks. The sample consist on ~2500 red clump stars in 11 bulge fields ($-10^\circ\leq l\leq+8^\circ$ and $-10^\circ\leq b\leq-4^\circ$), and a set of ~6300 disk stars selected for comparison. The bulge MDF is confirmed to be bimodal across the whole sampled area, with metal-poor stars dominating at high latitudes. The metal-rich stars exhibit bar-like kinematics and display a bimodality in their magnitude distribution, a feature which is tightly associated with the X-shape bulge. They overlap with the metal-rich end of the thin disk sequence in the [Mg/Fe] vs. [Fe/H] plane. Metal-poor bulge stars have a more isotropic hot kinematics and do not participate in the X-shape bulge. With similar Mg-enhancement levels, the position of the metal-poor bulge sequence "knee" is observed at [Fe/H]$_{knee}=-0.37\pm0.09$, being 0.06 dex higher than that of the thick disk. It suggests a higher SFR for the bulge than for the thick disk. Finally, we present a chemical evolution model that suitably fits the whole bulge sequence by assuming a fast ($<1$ Gyr) intense burst of stellar formation at early epochs. We associate metal-rich stars with the B/P bulge formed from the secular evolution of the early thin disk. On the other hand, the metal-poor subpopulation might be the product of an early prompt dissipative collapse dominated by massive stars. Nevertheless, our results do not allow us to firmly rule out the possibility that these stars come from the secular evolution of the early thick disk. This is the first time that an analysis of the bulge MDF and $α$-abundances has been performed in a large area on the basis of a homogeneous, fully spectroscopic analysis of high-resolution, high S/N data.

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。

↑