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巨大な惑星が 熱い巨大な恒星によって 極端な紫外線を浴びている
B Scott Gaudi1, Keivan G Stassun2,3, Karen A Collins2
1Department of Astronomy, The Ohio State University, Columbus, Ohio 43210, USA.
Nature
|June 6, 2017
まとめ
天文学者は A/B型の星を周回する超高温ガスの巨大惑星の KELT-9b を発見しました この極端な系外惑星は 強い恒星放射線により 大気を失っているようです
科学分野:
- 外惑星科学
- 星の天体物理学
- 惑星 の 大気
背景:
- 惑星の照射と消去は 恒星温度に左右されます
- 熱いA型恒星の周りを回る系外惑星は少ないが,B型恒星の周りを回る系外惑星は存在しない.
- WASP-33bはA型恒星の周りを回っており,太陽照射による高温と膨張を示しています.
研究 の 目的:
- 明るい恒星HD195689 (KELT-9) を周回する惑星の発見を報告する.
- 惑星KELT-9bとその宿主星を特徴づけるため
- KELT-9bの大気条件と質量損失率を調査する.
主な方法:
- HD 195689 (KELT-9) の観測
- 通過する巨大惑星の検出, KELT-9b.
- 恒星の温度と惑星の昼間の温度を測定する.
主要な成果:
- KELT-9bは母星の周りを約1.48日の周期で回っています.
- 宿主星KELT-9はA/B型境界で温度約10,170Kである.
- KELT-9bの昼間の温度は約4,600Kで,不透明性の源は原子金属である.
- KELT-9bはWASP-33bの700倍もの紫外線を受けます
結論:
- KELT-9bは超高温のガスの巨星で 大気は原子金属が支配している可能性が高い.
- 強い紫外線は 大気の大量減少を 示唆している
- KELT-9bは,主星のメインシーケンスの生涯にわたって,そのエンベロープを大きく剥がされる可能性があります.
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