エクソプラネットHD 189733bの地上からの近赤外線放射スペクトル
Mark R Swain1, Pieter Deroo, Caitlin A Griffith
1Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109-8099, USA. mark.r.swain@jpl.nasa.gov
Nature
|February 5, 2010
まとめ
地上からの赤外線スペクトロスコピーは,系外惑星HD 189733bのメタン (CH(4) 放射を検出しました. これは,非局所熱力学均衡 (non-LTE) 効果が,熱い木星の大気を理解するために重要であることを示唆しています.
科学分野:
- 外惑星科学とは,外惑星科学のこと.
- 大気スペクトロスコピーは,大気スペクトロスコピーを用います.
- アストロケミストリー アストロケミストリー
背景:
- 赤外線光譜は,系外惑星の大気の分析の鍵です.
- 以前の研究では,熱い木星の水,メタン,CO2,COが検出されました.
- 宇宙望遠鏡によってカバーされるスペクトル領域には限界がある.
研究 の 目的:
- HD 189733b系外惑星の昼間の放射スペクトルの地上からの観測を報告する.
- 以前の宇宙観測でカバーされていないスペクトル領域を調査する.
- 分子シグネチャーと大気条件を特定するために.
主な方法:
- 地上望遠鏡を使って赤外線観測を行いました.
- HD 189733bの放射スペクトルデータを集めたのは,2.0~2.4ミクロメートルから3.1~4.1ミクロメートルの範囲です.
- 結果を既存の宇宙ベースの測定値と比較した.
主要な成果:
- 観測されたスペクトルで明るい放射特性が検出されました.
- 重複する地域における宇宙ベースの測定に関する合意が確認されています.
- 3.25ミクロメートルの周囲で予期せぬ特徴を観測しました.
結論:
- 3.25マイクロメートルの特徴は,非局所的な熱力学均衡 (非LTE) メタン (CH4) 排出によるものである可能性が高い.
- この発見は,系外惑星の大気に対する局所熱力学均衡 (LTE) を仮定するモデルに挑戦しています.
- 強烈に照射された系外惑星からのデータを解釈する際には,非LTE効果を考慮する必要があります.
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