異常に金属が少ない球状星団の潮残骸
Zhen Wan1, Geraint F Lewis2, Ting S Li3,4,5,6
1Sydney Institute for Astronomy, School of Physics, The University of Sydney, Sydney, New South Wales, Australia.
Nature
|July 31, 2020
まとめ
フェニックス星流が発見されたのは 玉状星群の残骸で 金属の豊富さは 既知よりもはるかに低い
科学分野:
- 天文学と天体物理学
- 宇宙構造の形成
背景:
- 球状星団は銀河に存在する 古代の重力結合の星系です
- "金属性床"が観測され,0.3-0.4%未満の球状星団が見つかりませんでした.
- この床は,球状クラスター形成の最小質量と最大赤偏移を示します.
研究 の 目的:
- フェニックス星流の性質を調査する Milky Wayのハローのダイナミックに冷たい星流
- フェニックス川の祖先が 球状星団だったかどうかを判断し 金属性を評価する
- 球状星団の形成と進化に及ぼす影響を理解する.
主な方法:
- サザン・ステラ・ストリーム・スペクトロスコーピック・サーベイを用いたフェニックス星流のスペクトロスコーピック分析.
- 流の化学 (金属) 量,特に鉄 ([Fe/H]) を測定する.
- 流の性質を,既知の球状星群と理論モデルと比較する.
主要な成果:
- フェニックス星流の性質は 球体群の破壊された残骸と一致しています
- 流は,非常に低い金属度 ([Fe/H] = -2.7) を示し,確立された金属度フロアより大幅に低い.
- この発見は,これまでに発見された最も金属が少ない球状星団の祖先を特定しています.
結論:
- フェニックス・ストリームの存在は,観測された床より低い金属度を持つ球状群が存在したことを示唆している.
- これらの金属が少ない球状星団は 銀河系の進化の歴史の中で 破壊された可能性が高い.
- フェニックス・ストリームの祖先は,現在の球体群の集団とは異なる.
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