恒星の初期質量関数は,金属性と時間によって変化する
Jiadong Li1,2,3, Chao Liu4,5,6, Zhi-Yu Zhang7,8
1Key Laboratory of Space Astronomy and Technology, National Astronomical Observatories, Beijing, China.
Nature
|January 18, 2023
まとめ
恒星の初期質量関数 (IMF) は,銀河系の金属性や年齢によって変化します. 初期の恒星形成は低質量恒星が少なく,最近の恒星形成はより高い金属性を持つ低質量恒星を多く示しています.
科学分野:
- 天文学
- 天体物理学
- スター進化
背景:
- 星の初期質量関数 (IMF) は,銀河の構造と進化を理解するために重要です.
- 過去のIMFの観測は サンプルサイズが小さくて不確実性が高かった
- 議論は,IMFが一定であるか,または異なる環境で変化するかについて存在します.
研究 の 目的:
- 銀河の星群でIMFを調査する 前例のないサンプルサイズで
- IMFは金属と恒星の年齢によって変化するかどうかを判断する.
- 恒星形成モデルと銀河進化の研究の基準となる.
主な方法:
- 顕微鏡で観測された約9万3000のM矮星の星数分析を行った.
- 太陽の100〜300パーセックの星に 焦点を当てた
- 観測された恒星群を IMF と比較した.
主要な成果:
- 金属性や恒星の年齢に 依存する変数IMFの 明確な証拠を見つけました
- 金属性に関係なく,初期の恒星形成期に低質量恒星を観察した.
- 最近の恒星形成において,金属度が高い低質量恒星の割合が増加していることに注目した.
結論:
- IMFは普遍的ではありませんし 銀河系内での変動を示しています
- これらの発見は 恒星形成と銀河の化学的濃縮のモデルを 改訂することを必要としています
- IMF変数は銀河の質量推定と惑星形成効率の計算に影響する.
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