JWSTによる分断された12CO2と13CO2氷の観測
N G C Brunken1, A C A Boogert2, E F van Dishoeck3,1
1Leiden Observatory, 2300 RA Leiden, The Netherlands.
まとめ
恒星間CO2氷を加熱すると分離し,CO2メタノール混合物を形成します. 同位体比は氷の形成と熱化の段階における最小分化を示唆し,原星進化の洞察を提供している.
科学分野:
- 天体化学
- 星間媒体の物理
- プロトステラ進化
背景:
- 恒星間の氷は 化学的,熱的環境によって進化します
- 二酸化炭素 (CO2) 氷の振動モードは熱トレーサとして機能します.
- ジェームズ・ウェブ宇宙望遠鏡 (JWST) は,CO2の氷の特徴の詳細な観測を可能にします.
研究 の 目的:
- 高質量 (IRAS 20126) と低質量 (Per-emb 35) の原星におけるCO2氷の振動モードを分析する.
- CO2の氷の組成に対する氷の加熱と分離の影響を調査する.
- 二酸化炭素の氷の同位体比 (12C/13C) を決定し,分断を評価する.
主な方法:
- 近い赤外線と中赤外線のCO2氷のスペクトル観測
- 12CO2と13CO2のための15.2μmの曲げ,4.39μmの伸縮,および2.70μmの組み合わせモードの分析.
- 振動モードの一貫したプロファイルの分解は,氷の混合物をモデル化します.
主要な成果:
- 純粋なCO2氷の特徴的な二重ピークと13CO2と12CO2の短い波長ピークを観測した.
- CO2とCH3OHとH2Oの混合物によってモデル化された一貫したCO2の氷のプロフィールで,加熱時の分離を示します.
- 12CO2と13CO2のCO2コンポーネントの類似した貢献は,最小の同位体分化を示唆しています.
- IRAS 20126で得られた12C/13C_ice = 90 ± 9は,以前報告されたガスCOよりも低い.
- 15.64μmの純粋なCO2氷の13CO2曲折モードを検出しました.
結論:
- 加熱すると,CO2氷は水分豊富な層から分離し,CO2-CH3OH混合物を好みます.
- 二酸化炭素の氷の同位体比は,形成と加熱を通して一貫しており,限られた分断を意味しています.
- IRAS 20126で得られた12C/13C比は,原星の化学的進化に新たな制約を与える.
関連する概念動画
¹³C NMR: ¹H–¹³C Decoupling
1.2K
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...
1.2K
Hess's Law
46.1K
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.
46.1K
Atomic Emission Spectroscopy: Interference
272
In atomic emission spectroscopy (AES), high-temperature atomizers excite a broad range of elements and molecules that generate complex emissions from sources such as oxides, hydroxides, and flame combustion products in the flame or plasma. Several strategies can be employed to minimize spectral interferences caused by overlapping emission lines or bands. These include increasing instrument resolution, choosing alternative emission lines, optimally placing the detector in low-background regions,...
272
Emission Spectra
64.8K
When solids, liquids, or condensed gases are heated sufficiently, they radiate some of the excess energy as light. Photons produced in this manner have a range of energies, and thereby produce a continuous spectrum in which an unbroken series of wavelengths is present.
64.8K
Couette Flow
439
Couette flow represents the flow of fluid between two parallel plates, with one plate fixed and the other moving with a constant velocity. This configuration allows for a simplified analysis using the Navier-Stokes equations, which govern fluid motion under conditions of viscosity and incompressibility. For Couette flow, the assumptions include a steady, laminar, incompressible flow with a zero-pressure gradient in the flow direction. This flow type is beneficial for understanding shear-driven...
439
Isothermal Processes
4.0K
A thermodynamic process that occurs at constant temperature is called an isothermal process. Heat slowly flows into the system or out of the system to maintain thermal equilibrium. Processes involving phase changes like water evaporation into steam or freezing water into ice at a constant temperature are examples of Isothermal Processes.
An ideal gas can also undergo isothermal expansion or compression.
For example, consider 1 mole of an ideal gas inside an isolated cylinder at initial volume V...
An ideal gas can also undergo isothermal expansion or compression.
For example, consider 1 mole of an ideal gas inside an isolated cylinder at initial volume V...
4.0K


