银河系的低金属性气体的积聚
B P Wakker1, J C Howk, B D Savage
1Department of Astronomy, University of Wisconsin, Madison 53706, USA. wakker@astro.wisc.edu
Nature
|December 10, 1999
概括
科学家们发现了一个巨大的气体云落入银河系,其金属度是太阳值的0.09倍. 这一发现支持了银河系化学进化的模型和低金属度气体的持续下降.
科学领域:
- 银河系天文学 银河系天文学
- 宇宙化学 宇宙化学
- 天体物理学 天体物理学
背景情况:
- 银河系的化学进化模型需要持续的低金属度气体 (约. 0.1 太阳金属性).
- 这种落对于解决"G矮星问题"至关重要,因为它通过稀释恒星重元素的丰富度,并保持长寿恒星中狭窄的金属度范围来解决"G矮星问题".
- 在矮星系和银河系的外盘中,对银河系的衰落至关重要的低金属度气体被稀疏地观测到,远距离的观测发现了受湿的Lyα吸收器.
研究的目的:
- 为了研究一颗被观测到落入银河系盘中的巨大气体云的金属性和落入速度.
- 为了评估观察到的气体落入是否与银河系化学进化的理论预测保持一致.
主要方法:
- 对一个巨大的气体云进行光谱分析,以确定其金属性.
- 估计云的质量流速,以计算每单位面积的落入量.
主要成果:
- 一个巨大的云落在银河系盘中,其金属度是太阳值的0.09倍.
- 这一云的质量流速与每单位面积的落入量相对应,符合理论预期.
- 观测到的这种反射率大约是整个银河系所需的总速率的0.1-0.2倍.
结论:
- 这种低金属度降落云的发现提供了直接的观测证据,支持银河系化学进化的模型.
- 这些发现证实了低金属度气体积聚在维护银河系化学组成中的存在和重要性.
- 这项研究强调了持续的气体落入在调节银河系金属性和恒星形成中的重要性.
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