Lets learn something about space

Topic du jour: Neutron Stars AKA stellar phoenixes



We have learned about supernovas together before, and how if a star has enough mass, it will form a black hole post supernova. But what happens to a star after supernova when it isnt massive enough to form a black hole? When a star that has 4-8 times the mass of our sun explodes, the outer layers of the star are sent scattering across space, leaving nothing but a small, dense core to continue to collapse on itself. Our sun has a mass of 1.989x10^30 kilograms, so something 4-8 times the size of that is still not big enough to create a black hole. These cores are so dense, gravity pulls hard enough to combine protons and electrons, creating neutrons (subatomic particles with no net electric charge), hence the name neutron star.

How dense are neutron stars? The diameter of a neutron star is rough 12.5 miles with a mass of 1.5 times that of our sun (see above), which has a diameter of 864,337 miles. A single teaspoon of a neutron star weighs 1 billion tons. so 2 trillion pounds. lightweight. The gravity on a neutron star is 2 billion times more than that of the gravity on Earth. These stars spin up to 43,000 times per minute, gradually slowing over time.



Some neutron stars have materials streaming out of them at nearly the speed of light. These beams fly by earth and flash, much like light from a lighthouse. These are called pulsars. And much like a lighthouse navigating a seaward ship, astronomers can use these pulsars as navigation tools in space because of how predictable they are.



The average neutron star boasts a powerful magnetic field. Earth's magnetic field is around 1 gauss, and the sun's is around a few hundred gauss. But a neutron star has a trillion gauss magnetic field. Magnetars, a type of neutron star, have magnetic fields a thousand times stronger than the average neutron star, causing atoms to be distorted in shape, stretching out to be pencil shaped, when near these stars.



If a neutron star is part of a binary star system that survives the supernova, depending on the masses of the stars, a transfer of materials occurs. If the second star is more than 10 times as massive as our sun, transfers of material happen through stellar winds. If the second star is less than the mass of our sun, then transfers happen in something called a roche lobe:



So how does a neutron star die? typically, they cool down by emitting radiation and slow down their rotation. BUT, it is possible for netron stars to crash into each other, which is way cooler than just cooling off and slowing roation. This is called a "kilonova". The collision of two neutron stars made waves heard around the world in 2017, when researchers detected gravitational waves and light coming from the same cosmic smashup. The research also provided the first solid evidence that neutron star collisions are the source of much of the universe's gold, platinum and other heavy elements. The powerful collision released enormous amounts of light and created gravitational waves that rippled through the universe. But what happened to the two objects after their smashup remains a mystery.

"We don't actually know what happened to the objects at the end," David Shoemaker, a senior research scientist at MIT and a spokesman for the LIGO Scientific Collaboration, said at a 2017 news conference. "We don't know whether it's a black hole, a neutron star or something else."

This kilonova process looks something like this:


kilonovas, which are 1,000 times more powerful than regular star explosions (novas), also occur when neutron stars crash with black holes