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白い矮星を通過する小さな惑星
Andrew Vanderburg1, John Asher Johnson1, Saul Rappaport2
1Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA.
Nature
|October 23, 2015
まとめ
天文学者は白矮星WD 1145+017を周回する小惑星の崩壊を観測した. これは小惑星や小惑星からの岩石の破片が 白い矮星の大気を汚染している証拠です
科学分野:
- 天文学と天体物理学
- 星の進化について
- 外惑星科学
背景:
- ほとんどの恒星は 核燃料が尽きてから 白い矮星に進化します
- 多くの白矮星は重元素による大気汚染を示し,外部の補充を示唆しています.
- これらの元素の多量比は 太陽系の岩石の比に似ている.
研究 の 目的:
- 白い矮星の大気の重元素の起源を調査する
- 白い矮星の周りの岩石の分解を観察し特徴づけること
- 白い矮星に惑星の残骸が 蓄積されていることを 直接証明するために
主な方法:
- 通過フォトメトリを用いて白矮星WD1145+017を観測した.
- トランジットの信号の変数,深さ,プロフィールを分析した.
- 星のスペクトルで 重元素の線や 破片の存在を調べた
主要な成果:
- WD 1145+017を通過する少なくとも 1つ,おそらく複数の惑星が検出されました.
- トランジット信号は4. 5~4. 9時間の周期で発生し,異なる深さと非対称なプロファイルを示しました.
- 白い矮星は粉塵の残骸の円盤を持ち,重元素 (Mg, Al, Si, Ca, Fe, Ni) の顕著なスペクトル線を示しています.
結論:
- 観測された通過体は 崩壊する岩石の惑星系と一致します
- このシステムは 白い矮星の大気汚染が 小惑星のような 破壊された天体から生じるという 直接的な証拠を提供します
- この発見は,白矮星が以前の惑星系から残骸を蓄積するという仮説を裏付けている.
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