関連する実験動画
Updated: Oct 4, 2025
11:34
Scattering And Absorption of Light in Planetary Regoliths
Published on: July 1, 2019
10.5K
白い矮星が,X線観測によって決定された惑星物質を蓄積している
Tim Cunningham1,2, Peter J Wheatley3,4, Pier-Emmanuel Tremblay3,4
1Department of Physics, The University of Warwick, Coventry, UK. timothy.cunningham@warwick.ac.uk.
Nature
|February 10, 2022
まとめ
汚染された白矮星G29-38からのX線を検出しました 恒星モデルとは無関係な瞬間の増殖率を明らかにしました この発見は白矮星に 破片が蓄積されている 直接の証拠です
科学分野:
- 天文学と天体物理学
- 星の進化について
- 外惑星科学
背景:
- 多くの白矮星は重元素による大気汚染を示し,惑星の残骸の蓄積を示唆しています.
- 以前の証拠は間接的な光球金属検出に依存し 大気モデリングに大きく依存していました
- 蓄積率と組成を直接測定することは困難でした.
研究 の 目的:
- 汚染された白矮星G29-38の 瞬時の蓄積率を直接測定する
- X線放射を分析することで,継続的な残骸の蓄積の仮説をテストする.
- 恒星の大気モデルとは無関係に 蓄積率を制限する.
主な方法:
- 白い矮星G29-38からのX線放射が検出された.
- 測定されたX線光度を使用して瞬時の増量率を計算します.
- 蓄積物質のプラズマ温度を測定した.
主要な成果:
- X線光度から直接的なモデル独立の瞬時増量率を導出した.
- G29−38の蓄積率は,光球濃度から先程推定されたより高い.
- 低増量率モデルと一致する低血温度 (0. 5 ± 0. 2 keV) を測定した.
結論:
- X線検出は 白い矮星に残骸の蓄積が進行している直接的な証拠を提供します.
- より高い蓄積率は,現在の大気モデルの潜在的な限界を示唆し,おそらくコンベクティブオーバーショットを要求します.
- この発見は,白矮星が低速で増殖する 爆撃の解決策を支持する.
関連する概念動画
01:10Detection of Black Holes
2.3K
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...
2.3K
01:21Schwarzschild Radius and Event Horizon
2.2K
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...
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...
2.2K
01:18Conservation of Angular Momentum: Application
11.5K
A system's total angular momentum remains constant if the net external torque acting on the system is zero. Examples of such systems include a freely spinning bicycle tire that slows over time due to torque arising from friction, or the slowing of Earth's rotation over millions of years due to frictional forces exerted on tidal deformations. However in the absence of a net external torque, the angular momentum remains conserved. The conservation of angular momentum principle requires a...
11.5K
01:24X-ray Imaging
8.4K
German physicist Wilhelm Röntgen (1845–1923) was experimenting with electrical current when he discovered that a mysterious and invisible "ray" would pass through his flesh but leave an outline of his bones on a screen coated with a metal compound. In 1895, Röntgen made the first durable record of the internal parts of a living human: an "X-ray" image (as it came to be called) of his wife’s hand. Scientists worldwide quickly began their own experiments with...
8.4K
01:10Kepler's First Law of Planetary Motion
4.4K
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,...
4.4K
01:29Kepler's Second Law of Planetary Motion
4.5K
In the early 17th century, German astronomer and mathematician Johannes Kepler postulated three laws for the motion of planets in the solar system. His first law states that all planets orbit the Sun in an elliptical orbit, with the Sun at one of the ellipse's foci. Therefore, the distance of a planet from the Sun varies throughout its revolution around the Sun.
While in an elliptical orbit, the total energy of the planet is conserved. Therefore, the planet slows down when it is at apogee and...
While in an elliptical orbit, the total energy of the planet is conserved. Therefore, the planet slows down when it is at apogee and...
4.5K