H2D(+) 観測により,太陽のような星を形成する雲の核の年齢は少なくとも100万年であると推定されています
Sandra Brünken1, Olli Sipilä2, Edward T Chambers1
1I. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany.
Nature
|November 20, 2014
まとめ
恒星形成の核の年齢を決定することは困難です. ortho-およびpara-H2D (((+) の新しい観測により,密度の高い核が少なくとも100万年前のことを明らかにし,星形成のタイムラインを精製しました.
科学分野:
- 天文学と天体物理学について
- アストロケミストリー アストロケミストリー
- スター・フォーメーション
背景:
- 密集した星間雲の核の年齢は,星と惑星の形成を理解するために重要ですが,正確に測定することは困難です.
- N2H+でのデウテリウム分化などの以前の方法は,核の急速な収縮 (700,000年未満) を示唆していました.
- 分子水素 (H2) のオーソ/パラ比は,年齢の潜在的指標であるが,パラ-H2D+同位体は,歴史的に観測できなかった.
研究 の 目的:
- 密度の高い恒星間雲の核の年齢を決定するために,より敏感な化学時計を開発し,適用する.
- H2D+のオーソ/パラ比を用いて,IRAS 16293-2422 A/Bを収容する濃厚なコアの年齢を調査する.
主な方法:
- IRAS 16293-2422 A/B. 近くの濃い雲の中核で,オルト・H2D+とパラ・H2D+の放射と吸収が観察されました.
- H2D+ 移行周波数の実験室測定と,検出のための高度な機器を使用しました.
- 核の年齢を推論するために,オルソ/パラH2D+比を組み込んだ化学モデルを適用した.
主要な成果:
- 研究された濃厚な雲の中核で,オーソH2D+とパラH2D+の両方を成功裏に検出しました.
- オーソ/パラH2D+比は,核が少なくとも100万年前から化学処理を受けていることを示しています.
- この発見は,N2H+に基づく以前の推定とは対照的ですが,より長い恒星形成の時間スケールと一致しています.
結論:
- H2D+のオートホー/パラ比は,より古く,より進化した濃厚なコアにとって,信頼性の高い化学時計を提供します.
- 研究されたものを含む,密度の高い恒星形成の核は,おそらく約100万年の年齢を有する.
- この改訂されたタイムスケールは,星と惑星の形成のモデルに重大な影響を及ぼします.
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