银河系内部光环的年龄
1Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, Maryland 21218, USA. jkalirai@stsci.edu
Nature
|June 9, 2012
概括
白矮星为银河系中恒星群体的约会提供了更清晰的途径. 这项研究使用白矮星质量计算局部光环恒星的年龄,发现它们的年龄为11.4 ± 0.7亿年.
科学领域:
- 天文学和天体物理学
- 恒星进化 恒星进化
- 银河系考古学 银河系考古学
背景情况:
- 银河系包括不同的组成部分,如膨胀,圆盘和光环.
- 确定恒星群的组装历史是具有挑战性的,因为难以准确地测定低质量恒星的年龄.
- 白矮星,作为恒星进化的残余,提供了一个更可靠的方法来确定年龄.
研究的目的:
- 开发一种新的技术,使用白矮星来测定恒星群体的年龄.
- 为了确定银河系中局部场光环恒星的年龄.
- 改进我们对银河系组装历史的理解.
主要方法:
- 对银河系新形成的白矮星的观测.
- 对球状星团Messier 4中的白矮星的档案数据的分析.
- 测量白矮星质量分布和恒星进化模型的反转,以建立质量-年龄关系.
主要成果:
- 开发了一个数学关系,将白矮星的最终质量与原始质量和父群体年龄联系起来.
- 据计算,本地场光环恒星的年龄为11.4 ± 0.7亿年.
- 这个年龄与最古老的球状星团 (135亿年) 一致,但比它们年轻.
结论:
- 白矮星提供了一个强大的工具来约会银河系的组成部分.
- 当地光环恒星的年龄为了解银河系形成提供了一个关键数据点.
- 未来对光环白矮星的观测可以减少年龄的不确定性,并比较不同星系结构的形成时间.
相关概念视频
The Inner Mitochondrial Membrane
The inner mitochondrial membrane is the primary site of ATP synthesis. The inner membrane domain that forms a smooth layer adjacent to the outer membrane is called the inner boundary membrane. This domain contains membrane transporters that drive metabolites in and out of the mitochondria. In contrast, the inner membrane network that invaginates into the matrix space is called the cristae membrane. This domain accounts for principle mitochondrial function as it accommodates the protein...
Gravity between Spherical Bodies
Newton's law of gravitation describes the gravitational force between any two point masses. However, for extended spherical objects like the Earth, the Moon, and other planets, the law holds with an assumption that masses of spherical objects are concentrated at their respective centers.
This assumption can be proved easily by showing that the expression for gravitational potential energy between a hollow sphere of mass (M) and a point mass (m) is the same as it would be for a pair of extended...
This assumption can be proved easily by showing that the expression for gravitational potential energy between a hollow sphere of mass (M) and a point mass (m) is the same as it would be for a pair of extended...
Schwarzschild Radius and Event Horizon
No object with a finite mass can travel faster than the speed of light in a vacuum. This fact has an interesting consequence in the domain of extremely high gravitational fields.
The minimum speed required to launch a projectile from the surface of an object to which it is gravitationally bound so that it eventually escapes the object’s gravitational field is called the escape velocity. The escape velocity is independent of the mass of the object. Merging the idea of escape velocity with the...
The minimum speed required to launch a projectile from the surface of an object to which it is gravitationally bound so that it eventually escapes the object’s gravitational field is called the escape velocity. The escape velocity is independent of the mass of the object. Merging the idea of escape velocity with the...
Detection of Black Holes
Although black holes were theoretically postulated in the 1920s, they remained outside the domain of observational astronomy until the 1970s.
Their closest cousins are neutron stars, which are composed almost entirely of neutrons packed against each other, making them extremely dense. A neutron star has the same mass as the Sun but its diameter is only a few kilometers. Therefore, the escape velocity from their surface is close to the speed of light.
Not until the 1960s, when the first neutron...
Their closest cousins are neutron stars, which are composed almost entirely of neutrons packed against each other, making them extremely dense. A neutron star has the same mass as the Sun but its diameter is only a few kilometers. Therefore, the escape velocity from their surface is close to the speed of light.
Not until the 1960s, when the first neutron...
Gravitation Between Spherically Symmetric Masses
The gravitational potential energy between two spherically symmetric bodies can be calculated from the masses and the distance between the bodies, assuming that the center of mass is concentrated at the respective centers of the bodies.
Halo Effect
The halo effect is a cognitive bias in which an individual's overall impression influences judgments about their specific traits. This psychological phenomenon leads people to associate positive characteristics with those they perceive as generally good and negative characteristics with those they view as bad. This effect is particularly influential in social perception, professional evaluations, and decision-making processes.The Psychological Basis of the Halo EffectThe halo effect is rooted...


