恒星HD14156969の周りを回る原惑星円盤のCOとH3と+である
Sean D Brittain1, Terrence W Rettig
1University of Notre Dame, Center for Astrophysics, Notre Dame, Indiana 46556, USA.
Nature
|July 5, 2002
まとめ
研究者らは,巨大な恒星HD141569.9の周辺で一酸化炭素 (CO) と水素 (H3+) の放出を検出した. この発見は,巨大な恒星の周りのガス巨大惑星の急速な形成に関する手がかりを提供します.
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
- 恒星とガスディスクのダイナミクス
背景:
- 数多くの恒星の周りに巨大な惑星が検出されていますが,ガス巨大惑星の形成の時間スケールは重要な問題です.
- 巨大な恒星は,周囲のガスを素早く分散させ,原惑星の核の増殖を阻害する可能性がある.
- Herbig AeBeの恒星 (2〜3倍の太陽の質量) の周りの原惑星を検出することは,惑星形成の時間スケールを制限することができます.
研究 の 目的:
- 巨大な恒星の周りの惑星形成のタイムスケールを調査するために.
- エルビグ・エーベの恒星HD141569.9の周りの原惑星円盤の進化の証拠を探すためでした.
- HD141569.9の円盤内のガスと潜在的な原惑星の分布を分析する.
主な方法:
- 原惑星円盤から排出される一酸化炭素 (CO) の検出.
- 原惑星円盤からの三水素カチオン (H3+) 放射の検出.
- ディスクの組成と構造を推論するために,排出データの解釈.
主要な成果:
- 5~10百万年前のハービグ・エービー星HD141569.9から検出されたCOとH3+の放射.
- COデータによると,内部円盤は17天文学単位以上,初期の蓄積段階を過ぎて,クリアされている.
- COとH3+の同時存在は驚くべきことであり,COは通常H3+を破壊する.
結論:
- 観測されたCOとH3+は円盤内で空間的に分離されている可能性があります.
- また,H3+の放出は,原惑星の大気圏から発生する可能性がある.
- この検出は,巨大な恒星の周りの惑星形成過程の重要な証拠を提供します.
関連する概念動画
01:12The Nucleosome Core Particle
2.7K
Nucleosomes are the DNA-histone complex, where the DNA strand is wound around the histone core. The histone core is an octamer containing two copies of H2A, H2B, H3, and H4 histone proteins.
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their primary aim is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. On the other hand, they must allow polymerase enzymes to access histone-bound DNA during...
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their primary aim is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. On the other hand, they must allow polymerase enzymes to access histone-bound DNA during...
2.7K
02:10The Nucleosome Core Particle
15.3K
Nucleosomes are the DNA-histone complex, where the DNA strand is wound around the histone core. The histone core is an octamer containing two copies of H2A, H2B, H3, and H4 histone proteins.
The paradox
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their main responsibility is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. While on the other hand, they must allow polymerase enzymes to access DNA...
The paradox
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their main responsibility is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. While on the other hand, they must allow polymerase enzymes to access DNA...
15.3K
01:10Kepler's First Law of Planetary Motion
6.1K
In the early 17th century, German astronomer and mathematician Johannes Kepler postulated three laws for the motion of planets in the solar system. He formulated his first two laws based on the observations of his forebears, Nikolaus Copernicus and Tycho Brahe.
Polish astronomer Nikolaus Copernicus put forth a theory that stated a heliocentric model for the solar system. According to this heliocentric theory, all the planets, including Earth, orbit the Sun in circular orbits.
On the other hand,...
Polish astronomer Nikolaus Copernicus put forth a theory that stated a heliocentric model for the solar system. According to this heliocentric theory, all the planets, including Earth, orbit the Sun in circular orbits.
On the other hand,...
6.1K
01:04¹³C NMR: ¹H–¹³C Decoupling
2.1K
The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak splitting due to carbon-carbon spin-spin coupling is not observed in spectra. However, protons up to three sigma bonds away split the carbon signal according to the n+1 rule, resulting in complicated spectra.
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
2.1K
03:40Hess's Law
57.6K
There are two ways to determine the amount of heat involved in a chemical change: measure it experimentally, or calculate it from other experimentally determined enthalpy changes. Some reactions are difficult, if not impossible, to investigate and make accurate measurements for experimentally. And even when a reaction is not hard to perform or measure, it is convenient to be able to determine the heat involved in a reaction without having to perform an experiment.
57.6K
01:22Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
1.7K
Vicinal or three-bond coupling is commonly observed between protons attached to adjacent carbons. Here, nuclear spin information is primarily transferred via electron spin interactions between adjacent C‑H bond orbitals. This generally favors the antiparallel arrangement of spins, so 3J values are usually positive.
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the involved orbitals. The...
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the involved orbitals. The...
1.7K