R-process enhancements of Gaia-Enceladus in GALAH DR3
R-process enhancements of Gaia-Enceladus in GALAH DR3
复制标题
GALAH DR3 中 Gaia-Enceladus 的 R 进程增强
DOI：
10.1051/0004-6361/202040227
复制
发表时间：
2021
影响因子：
6.5
通讯作者：
Helmi A.
中科院分区：
文献类型：
--
作者：
Matsuno T.;Hirai Y.;Tarumi Y.;Hotokezaka K.;Tanaka M.;Helmi A.
尽管最近观测到了中子星星的合并，但r-过程元素的主要生产地点仍然不清楚。通过比较不同环境中的r-过程丰度，可以获得对站点属性的观测约束。的recentGaia释放和大样本的高分辨率光学光谱调查使我们能够比较的过程元素丰度之间形成的吸积矮星系，盖亚-土卫二，和那些形成在银河系。AimsOur的目的是了解的起源r-过程元素在盖亚-土卫二。MethodsWe首先构建了一个样本的恒星，使我们的研究Eu丰度不受检测限。然后，我们从银河系考古学与爱马仕（GALAH）DR 3，其中47和55星，分别运动学选择了76盖亚-土卫二星和81原位星，可以用来研究Eureliably.ResultsGaia-Enceladus星清楚地显示出较高的比率[Eu/Mg]比原位星。高[Eu/Mg]沿着低[Mg/Fe]也出现在相对大质量的卫星星系中，如LMC、天炉座和人马座矮星。另一方面，与这些星系不同的是，盖亚-土卫二没有显示出增强的[Ba/Eu]或[La/Eu]比率，这表明缺乏显着的过程贡献。通过与简单的化学演化模型的比较，我们发现，盖亚-土卫二的高[Eu/Mg]可以自然地解释为中子星合并的延迟时间分布遵循类似于Ia型超新星的幂律，但具有较短的最小延迟时间，这是由于中子星合并的过程富集。
ContextThe dominant site of production ofr-process elements remains unclear despite recent observations of a neutron star merger. Observational constraints on the properties of the sites can be obtained by comparingr-process abundances in different environments. The recentGaiadata releases and large samples from high-resolution optical spectroscopic surveys are enabling us to comparer-process element abundances between stars formed in an accreted dwarf galaxy, Gaia-Enceladus, and those formed in the Milky Way.AimsOur aim is to understand the origin ofr-process elements in Gaia-Enceladus.MethodsWe first constructed a sample of stars so that our study on Eu abundance is not affected by the detection limit. We then kinematically selected 76 Gaia-Enceladus stars and 81 in situ stars from the Galactic Archaeology with HERMES (GALAH) DR3, of which 47 and 55 stars, respectively, can be used to study Eu reliably.ResultsGaia-Enceladus stars clearly show higher ratios of [Eu/Mg] than in situ stars. High [Eu/Mg] along with low [Mg/Fe] are also seen in relatively massive satellite galaxies such as the LMC, Fornax, and Sagittarius dwarfs. On the other hand, unlike these galaxies, Gaia-Enceladus does not show enhanced [Ba/Eu] or [La/Eu] ratios suggesting a lack of significants-process contribution. From comparisons with simple chemical evolution models, we show that the high [Eu/Mg] of Gaia-Enceladus can naturally be explained by consideringr-process enrichment by neutron-star mergers with delay time distribution that follows a power-law similar to type Ia supernovae but with a shorter minimum delay time.