对元素起源的观测约束。III。在银河系Mn和Fe的化学演化中sub-Brachasekhar SN Ia起主导作用的证据
Observational constraints on the origin of the elements. III. Evidence for the dominant role of sub-Chandrasekhar SN Ia in the chemical evolution of Mn and Fe in the Galaxy
摘要：
晚型恒星中锰与铁的丰度比在很宽的金属丰度范围内对铁族元素的天体物理生产地点有严格的限制。在这项工作中，我们调查的Mn在银河系的化学演化使用高分辨率的光谱观测的恒星在银河系盘和晕星，以及一个样本的球状星团。我们的分析表明，局部热力学平衡（LTE）导致Mn I和Mn II线的电离平衡的强烈不平衡。锰我生产系统（高达0.6德克斯）较低的丰度相比，锰II线。非局部热力学平衡（NLTE）辐射转移满足整个金属丰度范围内的电离平衡，-3 < [Fe/H] <-1，导致元素两个电离阶段的丰度一致。我们比较了NLTE丰度与银河系化学演化模型计算使用不同来源的Ia型和II型超新星（SN Ia和SN II）产量。我们发现，一个很好的适合我们的观察，可以通过假设一个显着的（~ 75%）部分的超新星Ia干从一个sub-Chirasekhar（子Ch）通道。虽然这一比例大于早期研究中发现的比例（约50%），但我们注意到，我们仍然需要约25%的近Ch SNe Ia才能在[Fe/H] = 0时获得太阳能[Mn/Fe]。我们的新数据还表明，较高的SN II锰产量在低金属丰度比通常假设在文献中。
英文摘要：
The abundance ratios of manganese to iron in late-type stars across a wide metallicity range place tight constraints on the astrophysical production sites of Fe-group elements. In this work, we investigate the chemical evolution of Mn in the Milky Way galaxy using high-resolution spectroscopic observations of stars in the Galactic disc and halo stars, as well as a sample of globular clusters. Our analysis shows that local thermodynamic equilibrium (LTE) leads to a strong imbalance in the ionisation equilibrium of Mn I and Mn II lines. Mn I produces systematically (up to 0.6 dex) lower abundances compared to the Mn II lines. Non-local thermodynamic equilibrium (NLTE) radiative transfer satisfies the ionisation equilibrium across the entire metallicity range, -3 < [Fe/H] < -1, leading to consistent abundances from both ionisation stages of the element. We compare the NLTE abundances with Galactic Chemical Evolution models computed using different sources of type Ia and type II supernova (SN Ia and SN II) yields. We find that a good fit to our observations can be obtained by assuming that a significant (~ 75%) fraction of SNe Ia stem from a sub-Chandrasekhar (sub-Ch) channel. While this fraction is larger than that found in earlier studies (~ 50%), we note that we still require ~ 25% near-Ch SNe Ia to obtain solar [Mn/Fe] at [Fe/H] = 0. Our new data also suggest higher SN II Mn yields at low metallicity than typically assumed in the literature.
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