タイタンの熱帯湖の可能性は,暗い地形に関する観測から得られた
Caitlin A Griffith1, Juan M Lora, Jake Turner
1Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona 85721, USA. griffith@lpl.arizona.edu
Nature
|June 16, 2012
まとめ
タイタン (Titan) タイタン (Titan) タイタン (Titan)
科学分野:
- 惑星科学は惑星科学である.
- 天体生物学 アストロバイオロジー
- 大気科学 大気科学
背景:
- タイタンは,雲,雨,湖などの地球のような特徴を持っているが,メタンでできている.
- タイタンのメタンのほとんどは大気中のもので,表面液体は高緯度でしか検出されません.
- タイタンの熱帯地域は,表面液体ではなく,砂丘のフィールドが特徴です.
研究 の 目的:
- タイタンの低緯度地域における表面液体メタンの存在と起源を調査する.
- タイタンの表面の特徴の構成と特性を理解するためにスペクトルデータを分析する.
- 表面液体の観測された分布を,大気モデルと調和させるため.
主な方法:
- 緯度20°Nから20°Sまでの近赤外線スペクトル画像の分析
- 7つの波長の帯域にわたって,最も低い表面スペクトルフックスの領域を特定する.
- 表面のスペクトル特性を解釈するために放射伝送分析の適用.
主要な成果:
- 20°Nから20°Sの間には,例外的に低いスペクトルフックスの持久的な円領域 (60×40 km2) が特定されました.
- この領域のスペクトルサインは黒い表面と一致し,液体メタンの存在を示しています.
- この発見は,タイタンの表面液体の分布に関する以前の仮定に異議を唱えている.
結論:
- タイタンの永続的な低緯度湖は,地下の源から供給され,過去1万年以内に補給されている可能性が高い.
- これらの地下源は,タイタンの大気中のメタンの起源かもしれない.
- メタンの継続的な補充は,光化学的プロセスを通してタイタンの有機化学を維持するために不可欠です.
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