What Is #18: A Pulsar?

The 'What Is' Series

A couple of months ago I started a new series on this blog titled "What Is". Thus far the focus is on the field of astronomy where we hear all sorts of cool science taking place in space. The goal of this series is to explain the details of different objects we hear about relatively frequently.

A Neutron Star

Stars are big balls of gas that first become stars when they start fusing hydrogen into helium in their cores. After they use up their hydrogen supply in the core they can start fusing helium and potentially beyond. In the latter stages of a star's life, it goes through many, many changes, and is called many different things. Previously in this series I've discussed Red Giants, White Dwarfs, Neutron Stars, and many more, yet there are many types of stars I haven't discussed in this series. That includes pulsars. Pulsars are a separate subset of Neutron Stars.

Pulsar model - Michael Kramer

To put it simply, pulsars are neutron stars. Neutron stars rotate very rapidly, up to several thousand times per second. They emit a beam of radiation in each direction and if that beam of radiation points toward the Earth at any given time, Earth telescopes detect a repetitive signal. Thus the neutron star is called a pulsar for the pulsing. If the beam is not pointed to Earth, it is simply called a neutron star. 

Neutron stars are very small objects. They are the left over core of a high mass star that exploded as a supernova. What is left is the core that is packed down to a size of no more than 10-15 miles, maybe less. Yet the mass is very high at around a couple of solar masses. Thus a few suns are packed into the space of just a few miles! Therefore the density is extremely high and the gravitational force on the surface is tremendous. If you could survive a trip to a neutron star, you'd need a velocity of approximately half the speed of light to escape without being pulled back to the surface! WOW! 

Pulsars and neutron stars are very interesting objects. Just remember that a pulsar is a neutron star with a beam of radiation that swings past Earth.