外惑星 KELT-9b の大気中の原子鉄とチタン

H Jens Hoeijmakers^1,2, David Ehrenreich¹, Kevin Heng³

¹Observatoire astronomique de l'Université de Genève, Versoix, Switzerland.

Nature

|August 17, 2018

まとめ

天文学者は超熱の木星 KELT-9b の大気中に原子鉄とチタンを検出しましたこの発見は,大気組成を分析することによって,系外惑星形成の理論を制限するのに役立ちます.

科学分野:

外惑星科学
大気化学
恒星と系外惑星の大気

背景:

外惑星の形成の歴史を理解するには化学組成の知識が必要です
KELT-9bのような超高温の木星は,その極端な温度 (約 4,050 K) となっている.
このような高温では鉄のような耐火性元素が原子の形で存在しますが外惑星での鉄の検出は難しかったのです

研究の目的:

超高温の木星 KELT-9b の大気中の特定の原子種を検出し,特定する.
化学的バランスと組成を研究するために,KELT-9bのユニークな大気条件を利用します.
惑星形成の理論のための観測的制約を提供する.

主な方法:

恒星の前を通過するKELT-9bの高解像度スペクトルの取得.
特定の要素のスペクトルラインを特定するためにクロス相関分析の適用.
中性とイオン化された原子鉄 (Fe,Fe+) とイオン化された原子チタン (Ti+) を検出することに焦点を当てます.

主要な成果:

KELT-9bの大気中の中性および単離型原子鉄 (FeとFe+) の検出に成功した.
外惑星の大気中の単離型原子チタン (Ti+) の検出.
これらの検出は,熱い,雲のない系外惑星の大気圏における原子金属の存在の予測を裏付けている.

結論:

KELT-9bの大気中に原子鉄とチタンがあることが確認されました
超高温の木星で耐火性金属を検出する可能性を示しています
超高温の木星でも同様の観測が観測されれば惑星の形成と大気中の過程の理解が飛躍的に進みます

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