在低金属性矮星系WLM中发现密集的云核
Monica Rubio1, Bruce G Elmegreen2, Deidre A Hunter3
1Departamento de Astronomía, Universidad de Chile, Casilla 36-D, 8320000 Santiago, Chile.
Nature
|September 11, 2015
概括
在狼-隆德马克-梅洛特星系中观察一氧化碳 (CO) 云显示出典型的密度,解释了矮星系中恒星团的形成. 低云质量表明这些星团是小的,除非发生外部压缩.
科学领域:
- 天文学与天体物理学
- 银河系的演变
- 恒星形成
背景情况:
- 恒星的诞生需要观察分子云,主要由 (H2) 组成,并由一氧化碳 (CO) 追踪.
- 低金属度的环境,如形不规则星系,在密集的云层中对CO形成和生存构成挑战.
- 之前的CO检测限制阻碍了在这种低金属度系统中的恒星形成研究.
研究的目的:
- 为了研究低金属度矮星系Wolf-Lundmark-Melotte (WLM) 中的一氧化碳 (CO) 云的特性.
- 了解二氧化碳云对矮星系恒星团形成的影响.
- 探索外部触发因素在低金属度环境中形成巨大的恒星团中的作用.
主要方法:
- 在WLM星系中检测和分析二氧化碳云.
- 确定WLM的金属度为太阳能值的13%,远低于之前的CO检测值.
- 云的密度和柱子的密度与银河系的密度进行了比较.
主要成果:
- 在WLM中检测到CO云,尽管其金属含量低,但低于此前确定的检测值的50%.
- 这些云的密度和柱子密度与银河系的密度相当.
- 检测到的云相对于它们周围的原子和H2外来说很小.
结论:
- 在WLM云中的正常CO密度解释了在矮星系和巨型螺旋星系中形成的恒星团中观察到的类似密度.
- 这些二氧化碳云的低质量表明,WLM中的星团很可能是低质量的,除非受到星系规模压缩的影响.
- 在银河系的光环中形成的大型,金属贫乏的球状星团,可能源自矮星系,可能是由银河系撞击引发的.
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