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星の隠蔽から見た小惑星ハウメアの大きさ,形,密度,リング
J L Ortiz1, P Santos-Sanz1, B Sicardy2
1Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía S/N, 18008-Granada, Spain.
Nature
|October 13, 2017
まとめ
天文学者は,星隠蔽データを用いて,小惑星ハウメア周りのリングシステムを発見しました. この発見は,ハウメアについて新しい洞察をもたらします.
科学分野:
- 惑星科学
- 天文学
- 小惑星研究
背景:
- ハウメア (Haumea) は急速に回転する長方形の超海王星の矮星で,物理的な性質はほとんどない.
- チャリクロとキロンのような他の小さな太陽系天体の周りにリングシステムが観察されています.
研究 の 目的:
- ハウメアの物理的特徴,サイズ,形状,リング系の存在の可能性を調査する.
- ハウメアの密度とアルベドの見積もりを精査する.
主な方法:
- 複数の地球観測所を使用して,ハウメアの多弦恒星隠蔽観測を行った.
- 隠蔽中の二次イベントを分析し,潜在的なリング構造を特徴付けます.
- ハウメアの3次元形状と方向性を制限するために,光回転曲線と隠蔽データを組み合わせた.
主要な成果:
- ハウメア周りに0.5の不透明度,幅70km,半径約2,287kmのリングシステムが検出されました.
- この環はハウメアの赤道と,その衛星ヒヤカの軌道の共平線で,平均運動共振率3:1に近い位置にある.
- ハウメアの最大軸は少なくとも2,322 kmで,密度の上限は1,885 kg/m3で,幾何学的アルベドは0.51である.
- ハウメアの形状は三軸であり,水立状態の均質な体とは相容れない.
結論:
- ハウメアには,他の小さな天体に見られるものと同じような,かなりのリングシステムがあります.
- ハウメアの大きさ,密度,アルベドの新しい推定値は,理論的な期待と冥王星との比較とより一致しています.
- この研究は,ハウメアの物理的性質とその太陽系内の位置についての理解を洗練します.
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