(1) Ceresで太陽系の外部に起源を持つアンモニア化フィロシリケート
M C De Sanctis1, E Ammannito1,2, A Raponi1
1Istituto di Astrofisica e Planetologia Spaziali, INAF, Via del Fosso del Cavaliere 100, 00133 Roma, Italy.
Nature
|December 15, 2015
まとめ
矮星セレスのスペクトルは 広範囲に広がるアンモニアのフィロシリケートを示し 検出可能な水氷ではありません これは,太陽系外部の物質が形成中にセレスに組み込まれていたことを示唆している.
科学分野:
- 惑星科学
- 天体生物学
- ミネラロジー
背景:
- 矮惑星セレスの表面構成は議論されており,CIとCMの炭酸性コンドライトを含む類似物が提案されている.
- 以前の研究では,セレスの表面に粘土鉱物,アンモニア化フィロシリケート,またはブルシートがあることが示唆されました.
- 限られたスペクトルデータは,特に2.5〜2.9マイクロメートルの範囲で,表面材料の決定的な識別を妨げました.
研究 の 目的:
- 新しいスペクトルデータを用いて 矮星セレスの表面構成を調査する
- セレスの表面に存在する特定の鉱物や揮発性物質を特定する
- セレスの物質の起源と進化を理解するために
主な方法:
- 0.4〜5マイクロメートルの波長範囲でセレスのスペクトルを取得.
- 地表から約82,000kmから4,300kmまでの距離を測定した.
- ミネラロジカルシグネチャーを特定するためのスペクトルデータの分析.
主要な成果:
- 広範囲に広がったアンモニア化フィロシリケートがセレスの表面で検出されました.
- 表面に検出可能な水氷は見つかりませんでした.
- アンモニアはセレスの分化過程でフィロシリケートと反応した可能性がある.
結論:
- セレスの表面の構成は,アンモニア化フィロシリケートによって支配され,広範囲に広がる水の氷に関する以前の仮説に異議を唱える.
- アンモニアの存在は,太陽系外部の物質がセレスに組み込まれていることを示唆しています.
- これは,大太陽中心の距離での形成か,または後に揮発性物質の蓄積を意味する.
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