恒星群体由巨大的恒星占主导地位
Zhi-Yu Zhang1,2, D Romano3, R J Ivison4,5
1Institute for Astronomy, University of Edinburgh, Edinburgh, UK.
Nature
|June 6, 2018
概括
宇宙恒星形成的测量依赖于恒星初始质量函数 (IMF). 这项研究使用13CO/C18O比率在遥远的,尘埃遮蔽的星爆星系中发现了顶重的IMF,这表明恒星比以前的假设更大.
科学领域:
- 天文学与天体物理学
- 宇宙星系的形成
- 银河系的演变
背景情况:
- 准确的宇宙恒星形成率测量需要关于恒星初始质量函数 (IMF) 的假设.
- 国际货币基金组织的形状对于理解星系形成和宇宙时间的演变至关重要.
- 传统的IMF测定仅限于未被遮蔽的星系,
研究的目的:
- 在遥远的,被尘埃遮蔽的星爆星系中研究恒星初始质量函数 (IMF).
- 使用13C/18O同位素丰度比作为IMF的防尘标记物.
主要方法:
- 从四个尘埃覆盖的星爆星系中观察到的13CO和C18O辐射在红移z~2-3.
- 分析了13CO/C18O同位素丰度比作为国际货币基金组织的敏感指标.
- 使用化学进化模型,对银河系进行基准测试,以解释同位素比率.
主要成果:
- 在所有观测到的星爆星系中,都发现了极重的恒星初始质量函数 (IMF) 的明确证据.
- 目标中的13CO/C18O比率始终低,这意味着与本地星系相比,大质量恒星的比例更高.
- 这些发现表明大质量星体爆发事件可能比典型的形成星系中更大质量的恒星.
结论:
- 13C/18O同位素比为在尘埃遮蔽的环境中确定IMF提供了可靠的方法.
- 在高红移的星际爆发星系表现出显著的顶重IMF, 挑战以前的假设.
- 这种经过修订的IMF理解可能会使星际爆炸的高恒星形成率与银河系主序相协调.
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