初期の太陽星雲における鉄の同位体の均質性
1Department of Earth Sciences, University of Oxford, UK. xiangz@earth.ox.ac.uk
Nature
|July 19, 2001
まとめ
隕石や地球にある鉄の同位体は変化を示しているが,単一の線に収まり,初期の太陽星雲の均質化を示している. これは,惑星小積分とコンドルル形成の前に起こった.
科学分野:
- 宇宙化学 (コスモケミストリー)
- イソトープ地質化学とは
- 惑星科学は惑星科学である.
背景:
- 初期の太陽星雲の化学的および同位体均質性は,宇宙化学の重要な問題である.
- 複数の同位体を持つ元素の同位体研究は,太陽星雲の初期構成を明らかにすることができます.
- 隕石における酸素同位体の異常は,初期的な異質性や銀河の進化的影響を示唆している.
研究 の 目的:
- 隕石と地上のサンプルにおける鉄の同位体の組成を調べる.
- 鉄イソトープが太陽星雲の初期同質性を支持するか否かを判断する.
- 初期の太陽系プロセスと比較して,鉄同位体の均質化のタイミングを決定する.
主な方法:
- 3つの鉄同位体 (例えば,54Fe,57Fe,58Fe) の相対的豊富度を様々なサンプルで測定する.
- 三同位体図を用いた同位体データの分析.
- 地球外 (隕石) 物質と地球上の物質における同位体変動の比較.
主要な成果:
- 隕石と地上のサンプルの両方で,鉄同位素の豊富さの有意な変動が検出されました.
- すべての分析された太陽系物質は,3つの同位体図にプロットされると,単一の質量分数線に沿って並べられます.
- この配列は,鉄の同位体が太陽雲の中で質量分化と均質化を経験したことを示している.
結論:
- 太陽系における鉄の同位体は,当初同質の貯蔵庫と一致している.
- 鉄イソトープの均質化は,惑星小積分とコンドルル形成の前に太陽星雲で起こった.
- 鉄の同位体データは,初期の太陽雲の中で独特の鉄同位体シグネチャーを持つ明確な前駆物質の存在を支持しません.
関連する概念動画
Mass Spectrometry: Isotope Effect
3.8K
Most elements exist in nature as a mixture of isotopes. The isotopes differ in weight due to their respective number of neutrons. The molecular weight of a molecule is different depending on the specific isotope of its elements involved. As a result, the mass spectrum of the molecule exhibits peaks from the same fragment at multiple positions. The positions of these mass signals depend on the mass differences between isotopes. Furthermore, the intensity of these signals is dependent on the...
3.8K
Nuclear Stability
22.6K
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively charged protons together...
To hold positively charged protons together...
22.6K
Isotopes
63.0K
Elements have a set number of protons that determines their atomic number (Z). For example, all atoms with eight protons are oxygen; however, the number of neutrons can vary for atoms of the same element. The sum of the number of protons and the number of neutrons is the mass number (A). Atoms with the same atomic number but different mass numbers are called isotopes. Elements can have multiple isotopes, for example, carbon-12, carbon-13, and carbon-14.
An element's atomic mass, or weight,...
An element's atomic mass, or weight,...
63.0K
Atomic Mass
69.0K
Atoms — and the protons, neutrons, and electrons that compose them — are extremely small. For example, a carbon atom weighs less than 2 × 10−23 g. When describing the properties of tiny objects such as atoms, we use appropriately small units of measure, such as the atomic mass unit (amu). The amu was originally defined based on hydrogen, the lightest element, then later in terms of oxygen. Since 1961, it has been defined with regard to the most abundant isotope of carbon, atoms of which...
69.0K
Atomic Emission Spectroscopy: Overview
3.3K
Atomic emission spectroscopy (AES) is an analytical technique used to determine the elemental composition of a sample by analyzing the light emitted from excited atoms. In AES, atoms in a sample are excited to higher energy levels by thermal energy from high-temperature sources, such as plasma, arcs, or sparks. When these excited atoms return to lower energy states, they emit light at specific wavelengths characteristic of each element. The resulting atomic emission spectrum, which consists of...
3.3K
Atomic Nuclei: Nuclear Spin State Population Distribution
2.2K
Near absolute zero temperatures, in the presence of a magnetic field, the majority of nuclei prefer the lower energy spin-up state to the higher energy spin-down state. As temperatures increase, the energy from thermal collisions distributes the spins more equally between the two states. The Boltzmann distribution equation gives the ratio of the number of spins predicted in the spin −½ (N−) and spin +½ (N+) states.
2.2K


