太陽系外惑星からの赤外線放射
Drake Deming1, Sara Seager, L Jeremy Richardson
1Planetary Systems Laboratory and Goddard Center for Astrobiology, Code 693, NASA's Goddard Space Flight Center, Greenbelt, Maryland 20771, USA. Leo.D.Deming@nasa.gov
Nature
|March 24, 2005
まとめ
天文学者は,熱い木星HD 209458bから赤外線を検出し,木星が恒星によって加熱されていることを確認しました. この発見は,惑星が円形の軌道を持っている可能性を示唆し,その大きな大きさに関する以前の理論に挑戦しています.
科学分野:
- 天文学と天体物理学について
- エクソプラネット科学 エクソプラネット科学
背景:
- ホットジュピターは,恒星に非常に近い軌道を回るガスの巨大系外惑星です.
- これらの惑星は熱く,赤外線を放射することが予想されます.
- HD 209458bは,異常に大きな半径を持つ系外惑星であり,おそらく軌道特異性を要求する潮分散によるものです.
研究 の 目的:
- HD 209458b系外惑星からの赤外線を検出し,特徴づけること.
- HD 209458bの熱放出とその軌道の動力学への影響を調査する.
主な方法:
- HD 209458bの二次食の間,赤外線流 (24ミクロメートル) の減少を観測した.
- 惑星の通過に比べて二次食のタイミングを分析する.
主要な成果:
- HD 209458b (55 +/- 10 microJy) からの24マイクロメートルの赤外線を直接検出する.
- 1,130 +/- 150 Kの測定された明るさの温度,恒星照射と一致します.
- 2次日食のタイミングは,ほぼ円形の軌道を示し,軌道特異性を要する理論と矛盾しています.
結論:
- 検出された赤外線放射は,HD 209458bの恒星による有意な加熱を確認しています.
- 秒次日食の正確なタイミングは,HD 209458bが動的に微小な軌道離心率を持っていることを示唆しています.
- これは,軌道特異性によって引き起こされる潮の消散に依存する惑星の大きな半径の説明に挑戦しています.
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