低金属性ガスの蓄積は,天の川銀河によって行われます
B P Wakker1, J C Howk, B D Savage
1Department of Astronomy, University of Wisconsin, Madison 53706, USA. wakker@astro.wisc.edu
Nature
|December 10, 1999
まとめ
科学者たちは,太陽の0.09倍の金属性を持つ巨大なガス雲が,天の川銀河に落下していることを発見しました. この発見は,銀河の化学的進化のモデルと,低金属性のガスの連続的な流れを裏付けている.
科学分野:
- 銀河系天文学 銀河系天文学
- 宇宙化学 (コスモケミストリー)
- 天体物理学 天体物理学
背景:
- 銀河系の化学進化モデルでは,金属度が低いガス (約0.0%) が連続して落ち込んでいることを必要としている. 0.1 太陽の金属性).
- この落ち込みは,恒星の重元素濃縮を薄め,長寿命の恒星の狭い金属性範囲を維持することによって"G矮星問題"の解決に不可欠です.
- 銀河の崩壊に不可欠な低金属性ガスは,矮星銀河や天の川の外盤で希少に観測されており,水分化されたリアルファ吸収器の遠隔観測があります.
研究 の 目的:
- ミルクウェイの円盤に落ちていると観測された巨大なガス雲の金属性と転落率を調査するために.
- 観測されたガスインフォールが銀河化学進化の理論的予測と一致するかどうかを評価する.
主な方法:
- その金属性を決定するために,巨大なガスの雲を投下するスペクトル分析.
- 雲の質量流量率を推定し,面積単位あたりのインフォを計算する.
主要な成果:
- 銀河系の円盤に落ちる巨大な雲は,太陽の0.09倍の金属性を示しています.
- この雲の質量流速は,理論的な期待と一致する面積単位あたりのインフォールに対応しています.
- この観測されたインフォールは,銀河系全体に必要な総速度の約0.1-0.2倍を表しています.
結論:
- この低金属度降下雲の発見は,銀河化学進化のモデルを支持する直接的な観測証拠を提供します.
- この発見は,低金属性ガス蓄積の存在と,天の川の化学組成の維持における重要性を確認した.
- この研究は,銀河の金属化と恒星形成を調節する上で,進行中のガスインフォールの重要性を強調しています.
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