论文标题
来自高分辨率光谱V. molybdenum的磁盘和凸起巨头的丰度 - p过程元素
Abundances of disk and bulge giants from high-resolution optical spectra V. Molybdenum -- the p-process element
论文作者
论文摘要
目标。在这项工作中,我们旨在对局部磁盘和凸起的恒星种群中的中子捕获和p-process元素钼(MO)进行不同的比较,以最大程度地降低分析中可能的系统效应。方法。恒星样品由45个凸起和291个局部磁盘K-巨头组成,观察到具有高分辨率光谱。丰度是通过使用SME代码拟合合成光谱来确定的。使用丰度和运动学的组合将磁盘样品分离成薄和厚的盘组件。通过与先前发表的MO和中子捕获元素葡萄(CE)和Europium(EU)进行比较,研究和讨论了MO的宇宙起源。结果。我们确定了35个凸起和282个磁盘巨头的可靠mo丰度,分别为[mo/fe] 〜0.2和〜0.1 dex的典型不确定性,分别为凸起和磁盘。结论。我们发现,与厚的磁盘相比,[MO/FE]的凸起可能会增强,我们在[CE/FE]和[EU/FE]中都没有观察到。但是,这可能表明凸起中的恒星形成率更高,但是,由于我们没有观察到[EU/FE]中要增强的凸起,因此增强钼的起源尚未受到限制。虽然,散射很大,但我们可能会观察到p过程中有助于凸起化学演化的重元素产生的证据。
Aims. In this work, we aim to make a differential comparison of the neutron-capture and p-process element molybdenum (Mo) in the stellar populations in the local disk(s) and the bulge, focusing on minimising possible systematic effects in the analysis. Methods. The stellar sample consists of 45 bulge and 291 local disk K-giants, observed with high-resolution optical spectra. The abundances are determined by fitting synthetic spectra using the SME-code. The disk sample is separated into thin- and thick-disk components using a combination of abundances and kinematics. The cosmic origin of Mo is investigated and discussed by comparing with previous published abundances of Mo and the neutron-capture elements cerium (Ce) and europium (Eu). Results. We determine reliable Mo abundances for 35 bulge and 282 disk giants with a typical uncertainty of [Mo/Fe]~0.2 and ~0.1 dex for the bulge and disk, respectively. Conclusions. We find that the bulge possibly is enhanced in [Mo/Fe] compared to the thick disk, which we do not observe in either [Ce/Fe] nor [Eu/Fe]. This might suggest a higher past star-formation rate in the bulge, however, since we do not observe the bulge to be enhanced in [Eu/Fe], the origin of the molybdenum enhancement is yet to be constrained. Although, the scatter is large, we may be observing evidence of the p-process contributing to the heavy element production in the chemical evolution of the bulge.