Binary pulsar

Imagine two stars orbiting each other very closely in space. One of them is a tiny but super dense star called a neutron star, while the other is a more normal-sized star like our Sun. They are so close that they are locked in a tight gravitational embrace, almost like a dance.

Now, a pulsar is a type of neutron star that emits incredibly powerful beams of radio waves and other radiation as it spins rapidly on its axis. So, a binary pulsar is a system in which two pulsars orbit each other.

But why do we call it a "binary" pulsar? Well, "binary" means two things that are paired or twinned together, like a binary code that uses only two digits - 0 and 1. In this case, the two stars in the system are twinned together in their orbit around each other.

One of the most famous binary pulsars is called PSR B1913+16, also known as the Hulse-Taylor binary pulsar, in honor of the astronomers who discovered it. They found it by using radio telescopes to observe regularly timed pulses of radiation coming from a distant source in space.

As they studied the pulses more closely, they realized that they were coming from two stars circling each other in a tight orbit, with each one affecting the other's gravity and orbit. In fact, they were able to use the pulsar's timing and the Doppler effect to measure the stars' masses and confirm one of the predictions of Albert Einstein's theory of general relativity - that objects in orbit around each other will emit gravitational waves, which can in turn cause those objects to spiral closer together over time.

Binary pulsars are important tools for studying gravity and the properties of space-time, as well as the behavior of extreme objects like neutron stars. They can also help us learn more about the early history of the universe and the formation of stars and galaxies.