精致的食用者:黑洞逐渐消耗星星

Neutron Stars and Black HolesWhen massive stars reach the end of their life cycle, they can collapse into two extreme objects: neutron stars and black holes. Neutron stars are incredibly dense, with a mass greater than the Sun packed into a small space. Black holes are regions of space where gravity is so strong that nothing, not even light, can escape. Studying neutron stars and black holes helps scientists understand the most powerful forces in the universe.Science and Engineering Practices...

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...

Red Giants And White DwarfsStars go through different stages in their life cycles. After spending millions or even billions of years as a main sequence star, they begin to change. When a star exhausts its hydrogen fuel, it expands into a large, cooler red giant that glows reddish. Eventually, the outer layers drift away, leaving behind a white dwarf, a small, hot, and dense core. Understanding red giants and white dwarfs helps scientists learn how stars evolve and what happens at the end of...

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...

Star PowerStars are massive spheres of hot, glowing gases that produce energy through nuclear fusion. The energy from stars, including our Sun, powers the solar system by providing light and heat. Understanding how stars generate energy helps scientists learn about their life cycles, the formation of elements, and the forces that shape galaxies.Science and Engineering Practices (SEP): Developing and Using Models Scientists develop and use models to study how stars produce energy and interact...

Supergiants and SupernovasSome of the largest and most powerful stars in the universe are supergiants. These massive stars are much larger and brighter than our Sun. When a supergiant reaches the end of its life, it can explode in a massive event called a supernova. This explosion releases enormous amounts of energy and spreads elements across space. Understanding supergiants and supernovas helps scientists learn about the life cycle of stars and the formation of new elements in the...