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三つの古典的なセフェイド変数星は,天の川の核膨らみにある
Noriyuki Matsunaga1, Takahiro Kawadu, Shogo Nishiyama
1Kiso Observatory, Institute of Astronomy, University of Tokyo, 10762-30 Mitake, Kiso-machi, Kiso-gun, Nagano 397-0101, Japan. matsunaga@ioa.s.u-tokyo.ac.jp
Nature
|August 26, 2011
まとめ
銀河系の中核の膨らみで星が形成されるのは,エピソード的に起こった. 最近の星形成の爆発は,古典的なセフェイド変数によって示され,約2500万年前の活動を示唆しています.
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
- 銀河の進化について
背景:
- 銀河系の中核の膨らみ,半径約200パーセクの中心部には,複雑な星形成の歴史があります.
- この地域の星形成のトリガーとタイミングを理解することは,銀河の進化モデルにとって極めて重要です.
- 古典的なセフェイド変数は,その周期年齢関係により,星形成の年代を決定する方法を提供します.
研究 の 目的:
- ミルクウェイの核膨張の最近の恒星形成の歴史を調査するために.
- 銀河の中心近くの恒星形成活動の増加の特定の期間を特定するために.
主な方法:
- 恒星形成の歴史の探査機として古典的なセフェイド変星を用いた.
- 中央ブラックホールから40パーセク以内で見つかったセフェイドの脈動周期の分布を分析した.
主要な成果:
- 核の膨らみの中で,約20日間のパルス周期を持つ3つの古典的なセフェイドが検出されました.
- この特定の地域では,より長くまたはより短い期間を持つセフェイドは観察されなかった.
- 約2500万年前に恒星形成が増加した時期を推論し,最近まで拡大する可能性がある.
結論:
- 核の膨張は恒星形成のエピソードを経験し,2500万年前に顕著な爆発がありました.
- この最近の爆発は,3000万~7000万年前の活動が少ない時期と対照的です.
- この発見は,銀河の中心におけるガス含有量の変動によって引き起こされるエピソード的恒星形成のモデルを裏付けている.
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