極めて金属が乏しい銀河の恒星形成が非効率である
Yong Shi1, Lee Armus2, George Helou2
11] School of Astronomy and Space Science, Nanjing University, Nanjing 210093, China [2] Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093, China.
Nature
|October 17, 2014
まとめ
初期の宇宙では恒星形成は非常に非効率的でした. 近くの金属に乏しい銀河の観測は,恒星形成の効率が,今日の金属に富んだ銀河の十分の一未満であることを示しています.
科学分野:
- 天文学 (astronomy) 天文学 (astronomy) とは,天文学 (astronomy) とは,天文学 (astronomy) とは,天文学 (astronomy) とは
- 天体物理学 天体物理学
- コスモロジー・コスモロジーとは
背景:
- 初期の銀河は,金属度が非常に低いガス (ヘリウムよりも重い元素) から星を形成した.
- 低金属性は理論的には,ガスの冷却と効率的な恒星形成を妨げると予想されます.
- この阻害は,酸素濃度が太陽値の10%未満の銀河では直接観測されていません.
研究 の 目的:
- 非常に金属が少ない銀河の恒星形成効率を調査するために.
- 初期の宇宙における低金属性銀河の条件を理解する.
- 低金属度環境におけるガストレーサーの信頼性を評価する.
主な方法:
- 2つの非常に金属が少ない銀河 (酸素の豊富さ<太陽の10%) の空間的に解明された赤外線観測.
- これらの銀河内の7つの異なる恒星形成群の恒星形成の分析.
主要な成果:
- 観測された星群の恒星形成効率は,現在の金属に富んだ銀河の"0分の"以下であった.
- これらの低金属性環境では,非常に非効率な星形成が実証されています.
結論:
- この発見は,金属度が低いため,初期の宇宙では恒星形成の効率が著しく低下していたという仮説を裏付けている.
- 非常に金属が少ない銀河は,初期の宇宙時代を研究するための重要な局所的な類似点として機能します.
- 低金属度での従来のガストレーサー (CO,塵) の課題は,高度な観測技術の必要性を強調しています.
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