銀河系外部の渦巻き構造が水素で示されている
E S Levine1, Leo Blitz, Carl Heiles
1Astronomy Department, University of California, 601 Campbell Hall, Berkeley, CA 94720, USA. elevine@astron.berkeley.edu
Science (New York, N.Y.)
|June 3, 2006
まとめ
この研究は,銀河系の中性水素をマッピングし,25キロパーセックスを超えた非軸対称,多腕のスパイラル構造を明らかにしました. この詳細な地図は,私たちの銀河系に関する新しい洞察を提供します.
科学分野:
- 天文学と天体物理学について
- 銀河のダイナミクス
- スターラ・カルトグラフィー ステラ・カルトグラフィー
背景:
- 銀河系の大規模構造は伝統的に軸対称モデル化されていますが,非軸対称特性の観測証拠は増加しています.
- 中性水素 (HI) の分布と動態を理解することは,螺旋臂のマッピングと銀河円盤の範囲の決定に不可欠です.
研究 の 目的:
- 銀河系外側の円盤の中性水素の詳細な表面密度マップを作成する.
- 銀河系の螺旋構造を調査し,そのガスディスクの半径範囲を決定する.
- 銀河のスパイラルアームの形状と密度の変化を含む,銀河のスパイラルアームの性質を特徴付ける.
主な方法:
- 中性水素の混乱した表面密度をマッピングするために観測データの分析.
- 銀河南半球におけるスパイラル構造の識別と追跡.
- ピッチの角度を決定するために,観察されたスパイラルアームにログリズムスパイラルモデルをフィッティングする.
主要な成果:
- 銀河系が非軸対称で,複数腕の渦巻き銀河であることを確認しました.
- 螺旋状の構造は,外盤に明確に描かれ,少なくとも25キロパーセックに広がり,ガスディスクの最小半径を確立しています.
- 中性水素の表面密度の過密度は,ガスの厚さが減少した領域と相関し,腕に沿った表面密度比は比較的一定である.
- 傾き角が20度から25度までの対数螺旋は,観察された螺旋腕に正確に合致します.
結論:
- 詳細なHIマップは,銀河系の外盤に非軸対称,多腕のスパイラル構造が存在するという強力な証拠を提供します.
- ガス円盤は少なくとも25キロパーセックに広がっており,その構造は密度の変動と特定の螺旋臂の幾何学によって特徴付けられています.
- これらの発見は,銀河の形態学と渦巻き銀河におけるガスの分布に関する私たちの理解を洗練します.
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