大气中的分子斑块形成了AGB恒星的环恒星
L Velilla-Prieto1, J P Fonfría2, M Agúndez3
1Department of Molecular Astrophysics, Instituto de Física Fundamental, Madrid, Spain. l.velilla@csic.es.
Nature
|May 17, 2023
概括
观测显示了碳非对称巨分支 (AGB) 恒星大气中的块分子气体和尘埃. 这些结构由对流细胞和脉冲驱动,形成恒星周围的外.
科学领域:
- 天文学与天体物理学
- 恒星进化
- 恒星周围的环境
背景情况:
- 无对称巨分支 (AGB) 恒星喷射物质形成尘埃覆盖的外.
- 之前的观测显示在富含氧气的恒星附近有团状尘埃和不均的分子气体.
- 由于有限的分辨率,碳AGB恒星的尘埃形成区域的结构仍然不太清楚.
研究的目的:
- 在碳星AGBIRC+10°216的大气中研究分子气体和新形成的尘埃的分布.
- 了解碳AGB恒星中的物质排放机制.
- 在一个恒星半径的尺度上解析结构.
主要方法:
- 对IRC+10°216的大气进行高分辨率成像.
- 对分子气体线 (HCN,SiS,SiC2) 的观察.
- 对尘埃的形成和分布进行分析.
主要成果:
- 在不同的半径和单独的块中检测到HCN,SiS和SiC2线的不同分布.
- 解释这些块状分布为恒星光圈中的大型对流细胞.
- 观察到对流细胞与恒星脉冲结合,产生异构.
结论:
- 光球中的对流细胞,加上脉冲和潜在的伴侣,是塑造碳AGB恒星环恒星的关键驱动因素.
- 这些发现为恒星大气和尘埃形成区域中发生的过程提供了前所未有的细节.
- 这项研究有助于我们更好地理解恒星的质量损失和外形成.
相关概念视频
Kinetic Molecular Theory and Gas Laws Explain Properties of Gas Molecules
32.8K
The test of the kinetic molecular theory (KMT) and its postulates is its ability to explain and describe the behavior of a gas. The various gas laws (Boyle’s, Charles’s, Gay-Lussac’s, Avogadro’s, and Dalton’s laws) can be derived from the assumptions of the KMT, which have led chemists to believe that the assumptions of the theory accurately represent the properties of gas molecules.
32.8K
Atomic Absorption Spectroscopy: Atomization Methods
593
Atomic Absorption Spectroscopy (AAS) atomizes samples through flame atomization or electrothermal atomization. Flame atomization typically involves a nebulizer and spray chamber assembly to combine the sample with a fuel–oxidant mixture, creating a fine aerosol mist that enters a burner. Typically, the fuel and oxidant are combined in an approximately stoichiometric ratio. However, for atoms that are easily oxidized, a fuel-rich mixture may be more advantageous. Only about 5% of the...
593
Adiabatic Processes for an Ideal Gas
3.2K
When an ideal gas is compressed adiabatically, that is, without adding heat, work is done on it, and its temperature increases. In an adiabatic expansion, the gas does work, and its temperature drops. Adiabatic compressions actually occur in the cylinders of a car, where the compressions of the gas-air mixture take place so quickly that there is no time for the mixture to exchange heat with its environment. Nevertheless, because work is done on the mixture during the compression, its...
3.2K
Behavior of Gas Molecules: Molecular Diffusion, Mean Free Path, and Effusion
29.1K
Although gaseous molecules travel at tremendous speeds (hundreds of meters per second), they collide with other gaseous molecules and travel in many different directions before reaching the desired target. At room temperature, a gaseous molecule will experience billions of collisions per second. The mean free path is the average distance a molecule travels between collisions. The mean free path increases with decreasing pressure; in general, the mean free path for a gaseous molecule will be...
29.1K
Escape Velocities of Gases
972
To escape the Earth's gravity, an object near the top of the atmosphere at an altitude of 100 km must travel away from Earth at 11.1 km/s. This speed is called the escape velocity. The temperature at which gas molecules attain the rms speed, which is equal to the escape velocity, can be estimated by using the equation for the average kinetic energy of the gas molecules. According to the kinetic theory of gas, the average kinetic energy of the gas molecules is proportional to its...
972
Atomic Emission Spectroscopy: Overview
2.4K
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...
2.4K


