When a star explodes into a supernova, all that remains is a very small, extremely dense ball. This star is not made of gas, but rather of a liquid centre of subatomic particles called neutrons, surrounded by a solid iron crust. The matter in a neutron star is packed so tightly that the star is often no bigger than a few kilometres in diameter.
Neutron stars are city-size stellar objects with a mass about 1.4 times that of the sun. Born from the explosive death of another, larger stars, these tiny objects pack quite a punch. Let’s take a look at what they are, how they form, and how they vary.
When star four to eight times as massive as the sun explode in a violent supernova, their outer layers can blow off in an often-spectacular display, leaving behind a small, dense core that continues to collapse. Gravity presses the material in on itself so tightly that protons and electrons combine to make neutrons, yielding the name “neutron star.”
Neutron stars pack their mass inside a 20-kilometer (12.4 miles) diameter. They are so dense that a single teaspoon would weigh a billion tons — assuming you somehow managed to snag a sample without being captured by the body’s strong gravitational pull. On average, gravity on a neutron star is 2 billion times stronger than gravity on Earth. In fact, it’s strong enough to significantly bend radiation from the star in a process known as gravitational lensing, allowing astronomers to see some of the back side of the star.
The power from the supernova that birthed it gives the star an extremely quick rotation, causing it to spin several times in a second. Neutron stars can spin as fast as 43,000 times per minute, gradually slowing over time.
If a neutron star is part of a binary system that survived the deadly blast from its supernova (or if it captured a passing companion), things can get even more interesting. If the second star is less massive than the sun, it pulls mass from its companion into a Roche lobe, a balloon-like cloud of material that orbits the neutron star. Companion stars up to 10 times the sun’s mass create similar mass transfers that are more unstable and don’t last as long. Stars more than 10 times as massive as the sun transfer material in the form of stellar wind. The material flows along the magnetic poles of the neutron star, creating X-ray pulsations as it is heated.
By 2010, approximately 1,800 pulsars had been identified through radio detection, with another 70 found by gamma-rays. Some pulsars even have planets orbiting them — and some may turn into planets.
Picture Credit : Google
