在银河系边缘的分子PO和PN
L A Koelemay1, K R Gold1, L M Ziurys2,3
1Department of Chemistry, University of Arizona, Tucson, AZ, USA.
Nature
|November 8, 2023
概括
科学家使用PO和PN分子在外星系中检测到气相. 这一发现表明起源于非对称的巨型分支恒星, 而不是超新星, 挑战星系化学进化模型.
科学领域:
- 天文学与天体物理学
- 天体化学
- 银河系的化学进化
背景情况:
- 对于行星的形成和生物学至关重要,但以前只在银河系内部发现.
- 由于不良的原子转换,研究一直很困难.
- 目前的银河化学进化模型需要随意增加超新星的产生,以匹配观察到的丰度.
研究的目的:
- 在外星系探测气相.
- 在银河系研究的起源和分布.
- 改进银河系化学演变的模型.
主要方法:
- 对一氧化 (PO) 和化 (PN) 的毫米光谱的观察.
- 目标观测密集的云WB89-621,距离银河中心22.6千公里.
- 分析PO和PN的旋转线,以确定丰度.
主要成果:
- 在外星系中首次检测到气相.
- 在外星系观察到的PO和PN的数量与太阳系附近的数量相当.
- 在没有超新星的外星系中存在,
结论:
- 外星系中的很可能是由低质量非对称巨星分支 (AGB) 中的中子捕获过程产生的.
- AGB恒星也产生碳,可以解释观测到的含碳分子的大量和外星系的平坦金属度梯度.
- 这一发现需要对银河系化学进化的模型进行修订,
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