Neutron Stars

This video is part of a comprehensive series initially developed for William Paterson University and CUNY Hunter, aimed at supporting online classes and course materials for introductory astronomy. By engaging with all the videos within this series, you will effectively complete a full undergraduate course in astronomy, equipping yourself with the knowledge and skills necessary to navigate the night sky with confidence, learning all the basics and many advanced topics!

Neutron stars are among the most incredible and extreme objects in the universe. They’re like the final stages of the life cycle of massive stars. These stellar leftovers are super dense, have super strong gravity, and have unique states of matter. They’re often thought of as the bridge between regular matter and the mysterious world of black holes. They show the wildest forms of matter that can exist while still being considered matter. Neutrons are the main stuff in neutron stars, and they’re made when atomic nuclei collapse during a supernova explosion. A neutron star is formed when a massive star’s core collapses after it runs out of nuclear fuel. The outer layers of the star are blown away, but the core collapses under its own gravity. This makes a super compact object with a radius of about 6 miles and a mass bigger than the Sun. This extreme density leads to some really cool stuff, like “nuclear pasta,” which is the unique arrangement of nucleons in the neutron star’s interior. It’s thought to look like spaghetti and lasagna, and it helps us understand how matter behaves under extreme conditions. The extreme conditions inside neutron stars also cause a bunch of other cool things to happen. One of the most amazing things about neutron stars is how fast they spin. When they’re formed, they keep spinning because of something called conservation of angular momentum. They can spin really, really fast, sometimes even spinning a few times a second! As they spin, they create a strong magnetic field that’s up to a million times stronger than Earth’s. This magnetic dynamo powers the star to emit electromagnetic radiation, which is why neutron stars are divided into two types: pulsars and magnetars. Pulsars are like cosmic lighthouses, emitting beams of radiation as they spin. These beams sweep across space, creating regular signals that we can pick up from Earth. The Crab Pulsar, in the Crab Nebula, is a prime example of this. It shows how stars evolve and release super-high-energy radiation. Pulsars have been super helpful to scientists studying the universe. Their precise timing lets us explore basic physics, like testing Einstein’s theory of general relativity and how matter behaves under extreme gravity. Next, magnetars are a special type of neutron star with incredibly strong magnetic fields. They can be a thousand times stronger than regular pulsars! These powerful magnetic fields can cause huge bursts of gamma-ray and X-ray radiation, making them some of the most energetic sources in the universe. Their emissions can also affect the stuff around them, maybe even influencing star formation and the evolution of nearby stars and planets. The energy in neutron stars is mind-blowing. Imagine dropping a 0.75 kg hammer from a height of just one meter onto a neutron star. You’d get the explosive power of 176 tons of TNT! Neutron stars are not just fascinating subjects to study, they’re also crucial in astrophysics. Their interactions with other things around them can create all sorts of cool phenomena, like X-ray bursts. These happen when material from a companion star gets pulled onto the neutron star’s surface. This process releases a lot of energy, and we can see these bursts of X-ray radiation from far away. Neutron stars can also be involved in kilonovae, which are like cosmic fireworks caused by the merger of two neutron stars. These mergers create heavy elements by quickly capturing neutrons and releasing a ton of energy. They’re like cosmic factories that make the elements we see around us. Studying kilonovae, which are super-explosive events, has given us a lot of clues about how these heavy elements were formed. And guess what? Neutron stars are like cosmic puzzles that blend astrophysics, matter, and energy in the most fascinating way. Their unique properties and behaviors help us unravel the secrets of the universe’s fundamental nature.

0:00 Introduction
0:29 Life Cycles of Stars
1:38 Neutron Stars
5:27 Mass
13:16 Neutron Star Rotation
15:42 Temperature
18:07 Density and Pressure
27:43 Neutron Star Magnetic Field. No Really it's Big.
33:00 Structure of a Neutron Star
34:04 Nuclear Pasta on the Inside

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