熱い水蒸気は,輝く炭素星から流出する煙のような流れに含まれている
L Decin1, M Agúndez, M J Barlow
1Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium. Leen.Decin@ster.kuleuven.be
Nature
|September 3, 2010
まとめ
天文学者は,炭素恒星IRC+10216の内膜に水蒸気が豊富に存在することを発見し,これまでの恒星化学モデルに挑戦した. この発見は,紫外線光子が塊状の封筒に浸透し,水やその他の分子,例えばアンモニアを形成することを示唆しています.
科学分野:
- 天文学 天文学
- アストロケミストリー アストロケミストリー
- 恒星の進化について
背景:
- IRC +10216のような炭素に富んだ進化した星は,水蒸気が最小限にあることが予測されました.
- 以前の単一の水路の検出は,その起源について限られた洞察を提供しました.
研究 の 目的:
- IRC +10216.6の周周包膜に水蒸気の存在と起源を調査する.
- 炭素が豊富な恒星で水形成のための提案されたメカニズムをテストする.
主な方法:
- ハーシェル衛星を利用して,遠赤外線およびサブミリメートルスペクトルのIRC +10216を観測しました.
- 高興奮変遷を含む数十本の水蒸気線を分析した.
主要な成果:
- 多くの水蒸気線が検出され,かなりの豊富さを示しています.
- 熱い内層に水の存在を示唆する高興奮線が特定された (約. 1,000 K) となっている.
- アンモニアなどの他の分子の観察された豊富さは,予想よりも高かった.
結論:
- 暖かい内層の水蒸気は,深紫外線の光子が凝固した環状の封筒に浸透することによって形成される可能性が高い.
- このUVの浸透メカニズムは,アンモニアのような他の分子も形成する.
- この発見は,進化した炭素星における天体化学のモデルを改訂することを必要としている.
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