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相关概念视频

Nuclear Fusion02:45

Nuclear Fusion

The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process called fusion. The principal source of energy in the sun is a net fusion reaction in which four hydrogen nuclei fuse and ultimately produce one helium nucleus and two positrons.
A helium nucleus has a mass that is 0.7% less than that of four hydrogen nuclei; this lost mass is converted into energy during the fusion. This reaction produces about...
Nuclear Stability03:18

Nuclear Stability

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 in the...
Nuclear Fission02:50

Nuclear Fission

Many heavier elements with smaller binding energies per nucleon can decompose into more stable elements that have intermediate mass numbers and larger binding energies per nucleon—that is, mass numbers and binding energies per nucleon that are closer to the “peak” of the binding energy graph near 56. Sometimes neutrons are also produced. This decomposition of a large nucleus into smaller pieces is called fission. The breaking is rather random with the formation of a large number of different...
Schwarzschild Radius and Event Horizon01:21

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...
Detection of Black Holes01:10

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...
Nuclear Transmutation03:20

Nuclear Transmutation

Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with another particle. The first manmade nucleus was produced in Ernest Rutherford’s laboratory in 1919 by a transmutation reaction, the bombardment of one type of nuclei with other nuclei or with neutrons. Rutherford bombarded nitrogen-14 atoms with high-speed α particles from a natural radioactive isotope of radium and observed protons being...

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相关实验视频

Updated: Jun 22, 2026

Laser-heating and Radiance Spectrometry for the Study of Nuclear Materials in Conditions Simulating a Nuclear Power Plant Accident
09:18

Laser-heating and Radiance Spectrometry for the Study of Nuclear Materials in Conditions Simulating a Nuclear Power Plant Accident

Published on: December 14, 2017

一个低能量的核心崩超新星,没有气外.

S Valenti1, A Pastorello, E Cappellaro

  • 1Astrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, UK. s.valenti@qub.ac.uk

Nature
|June 5, 2009
PubMed
概括

天文学家发现了SN 2008ha,一个微弱的,缺乏的超新星. 这一发现可能将微弱的超新星与长时间的马射线爆发联系起来,以前与可见超新星无关.

更多相关视频

Setting Limits on Supersymmetry Using Simplified Models
07:46

Setting Limits on Supersymmetry Using Simplified Models

Published on: November 15, 2013

相关实验视频

Last Updated: Jun 22, 2026

Laser-heating and Radiance Spectrometry for the Study of Nuclear Materials in Conditions Simulating a Nuclear Power Plant Accident
09:18

Laser-heating and Radiance Spectrometry for the Study of Nuclear Materials in Conditions Simulating a Nuclear Power Plant Accident

Published on: December 14, 2017

Setting Limits on Supersymmetry Using Simplified Models
07:46

Setting Limits on Supersymmetry Using Simplified Models

Published on: November 15, 2013

科学领域:

  • * 天体物理学 * 天体物理学
  • * 恒星进化过程中的恒星进化
  • * 超新星物理学

背景情况:

  • * 由于强烈的恒星风,大质量恒星 (>25-30太阳质量) 可能成为缺水的沃尔夫-雷耶星.
  • *大质量恒星的核心崩可以产生低能超新星,其亮度微弱,动能低.
  • * 低能超新星的另一个来源是7-9太阳质量恒星中氧气-原子核的崩.
  • *此前,还没有观察到任何微弱的,缺乏的,核心崩的超新星.

研究的目的:

  • * 报道发现和特征的SN 2008ha,一个微弱的缺超新星.
  • * 调查类似的微弱超新星可能被错误地归类为特殊的热核事件 (类似于SN 2002cx).
  • * 探索微弱,脱离的核心崩超新星和长时间的马射线爆发之间的联系.

主要方法:

  • *观测天文学:探测和分析SN 2008ha.
  • *光谱分析以确定超新星属性 (例如,缺水,发光).
  • * 理论建模,将观察到的超新星特征与恒星进化路径联系起来.

主要成果:

  • *SN 2008ha被确定为一个微弱的,缺乏的超新星.
  • * 建议类似事件可能被错误地归类为类似SN 2002cx的超新星.
  • *在微弱,脱离的超新星和长时间的马射线爆发之间建立了潜在的联系.

结论:

  • *SN 2008ha代表了一类新的观测到的微弱超新星.
  • *类似事件的错误分类可以解释之前缺乏观察.
  • * 这一发现为长时间的马射线爆发提供了潜在的观测联系.